METROLOGY [ CAP. 454. 1 
CHAPTER 454 
METROLOGY ACT 
To repeal and replace the Weights and Measures Ordinance. 
( )* 
ACT XXV of 2002. 
PART I 
Preliminary 
Short title and 
commencement. 
1. (1) The short title of this Act is the Metrology Act. 
(2) This Act shall come into force on such date as the Minister 
responsible for industry may by notice in the Gazette appoint, and 
different dates may be so appointed for different purposes and for 
different provisions of this Act. 
Interpretation. 2. In this Act unless the context otherwise requires - 
Cap. 419. 
"Authority" means the Malta Standards Authority established by 
the Malta Standards Authority Act; 
"calibration" refers to all the operations for the purpose of 
determining the values of errors of a measuring instrument; 
"container" means a container in which goods are exposed, 
packed, offered for sale or sold, including, in particular, a bag, 
case, carton, bottle, glass, box, can, envelope, net, sack or wrapper, 
whether or not such wrapper fully encloses its contents; 
"conformity assessment procedures" has the meaning assigned to 
it by article 8; 
"Court" means the Court of Magistrates sitting as a court of 
criminal judicature; 
"Directorate" means the Metrology Directorate set up under 
article 3; 
"functions" includes powers and duties; 
"goods" means anything which may be the subject of trade or 
manufacture; 
Cap. 419. 
"Head" means the person appointed to the post of Head of the 
Metrology Directorate according to the provisions of article 3(17) 
of the Malta Standards Authority Act; 
"inspector" means a person authorised or appointed under article 
5 to be an inspector for the purposes of this Act; 
"legal metrology" means that part of metrology which deals with 
units of measurement, methods of measurement and of measuring 
instruments in relation to the mandatory technical and legal 
*Not yet in force.

2 CAP. 454.] METROLOGY 
requirements which have the object of ensuring the appropriate 
accuracy of measurements; 
"mark" or "marking" includes any inscription, stamp or label 
signifying conformity or otherwise of a measuring instrument with 
this Act and regulations made thereunder whether applied by 
impressing, casting, engraving, etching, branding or otherwise; 
"measurement standard" means a measuring instrument intended 
to define, to represent physically, to conserve or to reproduce the 
unit of measurement of a quantity, or a multiple or sub-multiple of 
that unit in order to transmit it to other measuring instruments by 
comparison; 
"measuring" means the act or process of appraising, assessing, 
calculating, calibrating, computing, estimating, evaluating or 
g a u g i n g o f l e n g t h , v o l u m e , w e i g h t o r m a g n i t u d e , a n d 
"measurement" shall be construed accordingly; 
"measuring instrument" means a device intended to be used to 
make measurements, alone or in conjunction with a supplementary 
device or devices; 
"Metrology" is the field of knowledge concerned with 
measurement, the principal fields of which are: units of 
measurement and their measurement standards, measurements and 
measuring instruments; 
"Minister" means the Minister responsible for industry and 
includes, to the extent of the authority given, any person authorised 
by the Minister in that behalf for any purpose of this Act; 
"ordinary measuring instrument" means a measuring instrument 
intended for ordinary use but not for the verification of other 
measuring instruments; 
"periodical verification" means a verification of a measuring 
instrument, not being an initial verification, which is carried out 
periodically, at such intervals and according to such procedures as 
may be established by the Directorate; 
"pre-package" means a product which has been placed in a 
container of whatever nature without the purchaser being present 
and where the quantity of the product contained in the package has 
a pre-determined value and cannot be altered without the package 
either being opened or undergoing a modification; 
"prescribed" means prescribed by regulations made under this 
Act; 
"prescribed purpose" refers to any of the purposes falling within 
the terms of article 7(1); 
"sell" includes offer, expose, advertise or keep for sale, and to 
supply by way of or for the purpose of consumption, and similar or 
related words shall be construed accordingly; 
"SI System" means the International System of Units, "SI", 
namely, the coherent system of units adopted and recommended by 
the 11th General Conference on Weights and Measures 
(Conférence Générale des Poids et Mesures - CGPM) in 1960, and

METROLOGY [ CAP. 454. 3 
as may be revised from time to time; 
"stamp" means a device used to apply a mark under this Act to a 
measuring instrument to indicate that it conforms to the 
requirements of verification; 
"stamping" includes any operation adopted for the purpose of 
applying to a measuring instrument the marks indicating that it 
conforms to the requirements of verification; 
"type approval" means the examination, including testing in 
accordance with international practices, and approval of a 
particular design or pattern of measuring instrument to show that it 
is suitable for use for a prescribed purpose and is capable of 
achieving the accuracies required; 
"unit verification" means the examination of a measuring 
instrument, generally of a unique design and intended for a specific 
application, to establish that it satisfies legal metrological 
requirements; 
"user" means the person or organisation responsible for the use 
of the measuring instrument for the purposes of this Act; 
"verification" means all the operations carried out by the 
Directorate, or by verifiers on its behalf, having the object of 
ascertaining and confirming that the measuring instrument entirely 
satisfies the requirements of this Act in respect of verification; 
"verification mark" means a mark applied to a measuring 
instrument certifying that the verification of the measuring 
instrument was carried out with satisfactory results; 
"verifier" means a person authorised or appointed under article 5 
to carry out verification within the meaning and for the purposes of 
this Act. 
PART II 
Administration 
The Metrology 
Directorate. 
Cap. 419. 
3. (1) The Malta Standards Authority shall have a directorate, 
to be styled the Metrology Directorate, which shall have the 
functions as may be assigned to it by this Act, by the Malta 
Standards Authority Act or by any other law. The provisions of the 
Malta Standards Authority Act shall apply to the Directorate. 
(2) The Head shall carry out such functions as are assigned to 
him by this Act or by regulations made thereunder or by any other 
law. 
(3) The Head shall furnish to the Authority such information 
regarding the performance of his functions as the Authority may 
from time to time request. 
(4) The Head and any other person as may be employed or 
otherwise appointed by the Authority to exercise functions under 
this Act shall not have any personal interest in the making, 
adjusting or selling of measuring instruments. 
The Metrology 
Advisory Board. 
4. (1) There shall be established a Metrology Advisory 
Board, the functions of which shall be:

4 CAP. 454.] METROLOGY 
(a) to provide advice of a scientific and technical nature to 
the Head and to provide assistance on general matters 
of policy and organisation relating to the functions and 
activities of the Directorate; and 
(b) to submit proposals and recommendations for new 
projects in the field of legal metrology. 
(2) The number of members, manner of procedure of their 
appointment and their terms of office shall be determined by the 
Authority, provided that the members shall be appointed from 
among persons enjoying technical expertise in legal metrology. 
(3) Administrative matters relating to the Metrology Advisory 
Board shall be conducted by the Head. 
Appointment of 
inspectors and 
verifiers. 
5. (1) The Authority may appoint any person being an officer 
of the Authority to be an inspector for the purposes of this Act. 
(2) The Directorate may appoint any person, whether physical 
or otherwise, to be a verifier for the purposes of this Act. 
(3) (a) The Directorate shall provide for the holding of 
examinations for the purpose of ascertaining whether persons 
possess sufficient skill and knowledge for the proper performance 
of the functions of inspectors and verifiers, and for the granting of 
certificates of qualification to persons who pass such examinations. 
(b) The Directorate shall establish the standard of skill and 
knowledge, as well as other requirements, needed for a person to 
qualify as inspector or verifier. 
(4) The Directorate shall ensure that the persons so appointed 
continue to meet the requirements laid down in accordance with 
subarticle (3). 
(5) Every person appointed under subarticles (1) and (2) as an 
inspector or as a verifier shall be furnished with a certificate of his 
appointment by the Directorate. Such certificate shall be valid for 
such period and may include such conditions as the Head may 
consider appropriate. 
(6) The Directorate may, if it deems fit, arrange with some 
other person to hold examinations for the purpose mentioned in 
subarticle (3). 
(7) No certificate of qualification shall be issued to any person 
who has not yet attained the age of eighteen. 
(8) There shall be charged, in respect of any examination which 
is held by the Directorate under this article, such fees as the 
Authority may from time to time determine. 
(9) The Authority may, upon the recommendation of the Head, 
and under such conditions as may be prescribed, at any time revoke 
an appointment made under this article, and in such case, the 
person whose appointment is so revoked shall surrender to the 
Directorate the certificate furnished under this article. 
(10) The Directorate shall monitor the activities of the verifiers 
appointed under this Act.

METROLOGY [ CAP. 454. 5 
Powers of 
inspectors. 
6. (1) An inspector duly appointed in terms of this Act, in the 
discharge of his duties, shall have the following powers: 
(a) to enter and search any industrial establishment or 
commercial premises or vehicles or vessels, where a 
measuring instrument which is meant to be used for 
any prescribed purpose, is installed or kept, or where 
there is reason to believe it is installed or kept; 
(b) to enter any premises or any other place, including a 
vehicle or vessel, in which any activity in connection 
with the manufacturing, processing, supplying, 
distributing, importing or wholesale or retail selling of 
goods is carried on; 
(c) to inspect such premises and examine and test any 
such measuring instruments or goods found thereon 
for the purposes of establishing conformity with the 
provisions of this Act; 
(d) to apply non-conformity marks to the measuring 
instrument if, following any such inspection or testing, 
a measuring instrument is found not to be in 
conformity with the provisions of this Act; 
(e) to remove from the premises for examination, testing 
and measuring any goods or measuring instrument to 
which a non-conformity mark has been applied; 
(f) to require the owner, the person in charge or any 
employee in charge of or at the place entered to 
provide all reasonable assistance including personal 
assistance, and to produce books, records and written 
or electronic documents to enable the inspector to 
carry out his functions under this Act; 
(g) to inspect and copy or take extracts from any such 
books, records or other documents; and 
(h) in the case of any vehicle or vessel referred to in 
paragraph (a), to request the owner or operator thereof 
to bring the vehicle or vessel for examination to a 
location as may be indicated to him by the inspector. 
(2) An inspector who removes a measuring instrument or goods 
pursuant to subarticle (1)(e) shall notify forthwith, and issue a 
receipt to, the person from whose premises the measuring 
instrument or goods are taken, or that person’s authorised 
representative, indicating that the measuring instrument or goods, 
as the case may be, are taken in pursuance of this Act. 
(3) No entry and search shall be effected outside the normal 
business hours of the establishment concerned, unless the Head has 
cause to believe that delay could cause the loss or suppression of 
any evidence or may otherwise prejudice the outcome of the search. 
(4) An inspector may seize and retain: 
(a) any article, measuring instrument, stamp or goods 
which he believes to be in contravention of this Act; 
and

6 CAP. 454.] METROLOGY 
(b) any document relating to a measuring instrument or 
any document displayed with any goods offered or 
exposed for sale which relates to the price or quantity 
of the goods, and which the inspector believes may be 
required as evidence in any proceedings. 
(5) Any person who - 
(a) obstructs or impedes an inspector in the exercise of his 
functions, or does not comply with a requirement made 
by an inspector in carrying out any of his functions 
under this Act, or 
(b) refuses or fails to give an inspector any assistance or 
information which the inspector may request in the 
performance of any of his functions under this Act, or 
(c) makes an incorrect, false or misleading statement, 
either verbally or in writing, to an inspector who is 
engaged in carrying out any of his functions under this 
Act, 
shall be guilty of an offence under this Act. 
(6) Where it results to an inspector that a measuring instrument 
or a measurement standard fails to give the correct measurement 
which it purports to give or is otherwise faulty, the inspector may 
give the person responsible a written notice ordering him that, until 
such time as the said notice is withdrawn, the measuring instrument 
shall not be used and, where applicable, shall be removed. Any 
person who knowingly acts in contravention of such written notice 
shall be guilty of an offence under this Act. 
(7) The Head may exercise any of the powers conferred on an 
inspector under this article. 
(8) In the course of any entry and search under this article, the 
Head may request the assistance of the Police. 
(9) In the exercise of any powers conferred by this article, the 
inspector shall, if so requested, provide evidence of his 
appointment. 
(10) The inspector may be accompanied by such other persons 
and take with him such instruments as are necessary for the purpose 
of carrying out his functions.
PART III 
Control Procedures of Measuring Instruments, Measurements, 
Product Quantities and Pre-packages 
Metrological 
controls of 
measuring 
instruments. 
7. (1) Measuring instruments used or intended to be used for 
certain measurements, including: 
(a) measuring instruments used for the verification of 
ordinary measuring instruments; 
(b) measuring instruments used for transactions in goods 
and services, fiscal or postal transactions, or for 
analogous or similar purposes in pursuance of a trade 
or business;

METROLOGY [ CAP. 454. 7 
(c) measuring instruments used in or for the enforcement 
of this Act or of any other law; and 
(d) measuring instruments used in the field of public 
health, safety or environmental protection, 
as may be prescribed shall be subject to metrological controls. 
(2) Only measuring instruments that have successfully 
undergone the controls listed under article 8(2) and such other 
controls as may be established by the Directorate may be used for 
any prescribed purpose. 
(3) Persons importing, manufacturing, repairing, selling, 
hiring, using or otherwise dealing in measuring instruments within 
the meaning of subarticle (1), must inform the Directorate of their 
activity and become registered with it within such timeframes as 
the Directorate may establish by notice in the Gazette, and different 
timeframes may be established for different categories or classes of 
measuring instruments. For this purpose, the Directorate shall 
maintain a register of such persons, and it shall have the power to 
require any such person to furnish it with any information, 
documentation and undertakings as it may deem fit. 
(4) Any person who fails or neglects to comply with the 
provisions of subarticles (1), (2) or (3) shall be guilty of an offence. 
(5) Where, in the special circumstances of any particular case, 
it appears to the Directorate that it would be impracticable or 
unnecessary that a particular measuring instrument be subjected to 
metrological controls in terms of this article, the Directorate may, 
by an exemption in writing, dispense with such requirement. The 
Directorate may attach any conditions, including a time limit, to 
any such exemption and any person who contravenes any condition 
attached to an exemption shall be guilty of an offence. 
(6) For the purposes of this article, "measuring instrument" 
shall include any measuring instruments used or offered for use by 
private or public undertakings. 
Conformity 
assessment 
procedures. 
8. (1) Measuring instruments intended for use for any 
prescribed purpose, including public weighing, shall be subject to 
such conformity assessment procedures as may be prescribed by 
the Directorate by notice published in the Gazette. 
(2) The conformity assessment procedure may include such 
controls as may be prescribed by the Directorate, and may include: 
(a) type approval; 
(b) initial verification; 
(c) verification after repair or modification; 
(d) periodical verification; 
(e) supervision of the procedures effecting the use or 
operation of measuring instruments. 
(3) The Directorate shall certify whether or not the measuring 
instrument has successfully undergone the conformity assessment 
procedures adopted in its regard in terms of subarticle (2):

8 CAP. 454.] METROLOGY 
Provided that a certificate of conformity issued by an 
inspector or a verifier duly appointed in terms of article 5 shall be 
valid and effective as if issued by the Directorate. 
Marking of 
measuring 
instruments. 
9. (1) Measuring instruments which have been subject to the 
conformity assessment and inspection procedures and which have 
been found to conform to the relative requirement shall have 
affixed, stamped, marked or otherwise applied on them marks 
signifying their conformity to the relevant requirement or provided 
with corresponding certificates and shall accordingly qualify as a 
"legally controlled measuring instrument". These marks, their 
form, design, application or obliteration together with facilities for 
receiving such marks shall be prescribed by the Directorate which, 
for the purposes of this subarticle, may impose additional 
requirements in any matter related to the measuring instrument 
itself. 
(2) A measuring instrument which has not undergone these 
controls successfully may be given a rejection mark and must be 
modified, repaired or withdrawn. These marks, their form, design, 
application or obliteration together with facilities for receiving 
such marks shall be prescribed by the Directorate. 
(3) Only persons duly authorized by the Directorate may mark 
or stamp a measuring instrument with metrological control marks 
in terms of subarticles (1) and (2). 
(4) In the event that any marks that should be applied in terms 
of this article present any difficulty, the Directorate may establish 
alternative forms or means of application. 
(5) Stamps shall be made of such material as is determined by 
the Directorate. 
(6) Any measuring instrument to which a rejection mark has 
been affixed, stamped, marked or otherwise applied in terms of this 
article shall not be used for any prescribed purpose. 
(7) Any person keeping or using, for any transaction falling 
within any prescribed purpose, any false or inaccurate measuring 
instrument or any measuring instrument which does not bear a 
verification mark or which bears a rejection mark shall be guilty of 
an offence. 
(8) For the purposes of this article: 
(a) "legally controlled measuring instrument" means a 
measuring instrument which conforms to prescribed 
requirements, in particular legal metrological 
requirements; and 
(b) "rejection mark" means a mark or seal applied to a 
measuring instrument in a conspicuous manner to 
indicate that the measuring instrument does not 
comply with the statutory requirements and 
obliterating any previously applied verification mark. 
Sealing and 
securing measuring 
instruments. 
10. (1) The calibration device on a measuring instrument shall 
be secured in such a manner as to enable an adjustment to be

METROLOGY [ CAP. 454. 9 
detected whether on verification or otherwise. 
(2) The means by which a calibration device shall be secured 
shall be provided by the manufacturer, supplier or user of the 
measuring instrument. 
(3) The Directorate may, from time to time, prescribe specific 
requirements on the sealing or securing of measuring instruments. 
Adjusting of 
measuring 
instruments. 
11. (1) In circumstances as may be determined by the 
Directorate, any measuring instrument or particular type of 
measuring instrument may be adjusted by an inspector. 
(2) Where, on examination by an inspector, a measuring 
instrument is found to be inaccurate, and adjustment of the 
m e a s u r i n g i n s t r u m e n t i s n e c e s s a r y i n o r d e r t o r e n d e r i t 
metrologically accurate, the inspector shall: 
(a) notify the owner of the measuring instrument or the 
owner’s authorised representative accordingly, 
detailing the results of the examination; and 
(b) request the owner or his representative either to have 
the work carried out by a third party or to empower the 
inspector to undertake the necessary adjustment. 
(3) The owner or his representative shall bear any costs arising 
from any adjustment as is referred to in subarticles (1) and (2). 
Liability of certain 
measurements to 
metrological 
controls. 
12. (1) Any measurements that may result from the use of any 
prescribed purpose may be subject to metrological controls. 
(2) The Minister, acting on the advice of the Authority, may 
define the measurements that are subject to such controls. 
(3) The Directorate may establish the methods and procedures 
for the undertaking of such controls as it may deem appropriate. 
Metrological 
control of product 
quantities and prepackages 
delivered 
or exposed for sale. 
13. (1) Where a transaction may involve the delivery of a 
definite quantity of a product or an offer for sale involving the 
indication or labelling of a definite quantity of the product, these 
product quantities may be subject to metrological controls. 
(2) The Directorate may, from time to time, establish 
requirements relating to the control methods and the metrological 
conditions with which quantities of products and pre-packages 
must comply, and may define permissible tolerances or variations 
on quantities. 
(3) Any person who, for the purposes of trade or business, 
sells, buys or offers to buy, delivers or causes to be delivered, any 
goods by weight, by quantity, by number of items or by any other 
measure, which does not satisfy the requirements established under 
this article or any other provision of this Act, shall be guilty of an 
offence.

10 CAP. 454.] METROLOGY 
PART IV 
Authorised Units and Measurement Standards 
Legal units of 
measurement. 
14. (1) The units of measurement which are authorised for the 
purposes of this Act and for any other purposes of law shall be 
those listed in the First Schedule. Such units shall be used for all 
transactions which directly or indirectly involve a measurement. 
(2) The only lawfully permissible linear, capacity and weight 
standard measures that may be used for any prescribed purpose 
shall be those set out in the Second Schedule. 
(3) For all purposes of law, the conversion of a unit of 
measurement listed in the First Schedule to another unit of 
measurement not so listed shall be calculated on the basis of the 
tables of equivalence laid down in the Third Schedule. 
(4) The Fourth Schedule shall be used in the interpretation and 
application of the provisions of the First Schedule. 
Denominations of 
measurement 
standard. 
15. (1) No person shall hold or have in his possession for any 
prescribed purpose any linear, capacity or weight standard measure 
which is not of a denomination shown in the Second Schedule. 
(2) Any person who contravenes the provisions of subarticle 
(1) shall be guilty of an offence. 
Measurement 
standards. 
16. (1) The Authority shall provide, maintain or cause to be 
maintained such measurement standards including facilities, 
equipment and reference materials as are considered necessary 
from time to time to facilitate the realisation and dissemination of 
the SI System of Units of measurement, and to make funding 
available for such purposes. 
(2) For the purpose of subarticle (1), the Authority may, upon 
the recommendation of the Head, designate and delegate other 
organisations to be responsible bodies in specialised fields of 
measurement. 
(3) The Head may prescribe the measurement standards 
maintained under subarticles (1) or (2) and the conditions of their 
maintenance, including traceability, custody and the intervals 
within which the values of measurement standards shall be 
determined. 
(4) Where any doubt arises as to the continued conformity of a 
measurement standard with the appropriate permissible limits of 
error, the measurement standard shall not be used until its value has 
been redetermined or it has been replaced by a measurement 
standard conforming to the appropriate permissible limits of error. 
An up-to-date certificate of traceability shall be maintained in 
respect of every measurement standard or set of measurement 
standards maintained by the Directorate or any organisation 
designated under subarticle (2). 
(5) For the purposes of this article: 
(a) "reference material" means a material one or more of 
whose properties are sufficiently homogeneous to be

METROLOGY [ CAP. 454. 11 
used for the calibration of an apparatus, the assessment 
of a measurement method or the assignment of values 
to materials; and 
(b) "traceability" means the property of the result of a 
measurement which is related, through an unbroken 
chain of comparisons, to international measurement 
standards. 
PART V 
General provisions 
Public weighers. 17. (1) No person shall act as a public weigher unless 
authorised by the Directorate. 
(2) No authorisation shall be granted to any person in terms of 
subarticle (1) unless - 
(a) he has attained the age of eighteen years; 
(b) he has been found guilty of fraud or of an offence 
affecting public trust; and 
(c) he has passed a qualifying examination set by the 
Directorate. 
(3) Any person acting as a public weigher without the 
necessary authorisation from the Directorate shall be guilty of an 
offence. 
(4) The Directorate may, from time to time, issue requirements 
and guidelines for persons undertaking the activity of public 
weighers. 
Public officers. 
Cap. 9. 
18. The officers of the Directorate shall be deemed to be public 
officers for all purposes of the Criminal Code. 
Regulations. 19. (1) The Minister may, on the advice of the Authority, 
make regulations - 
(a) imposing requirements in relation to any matter related 
to the pre-packaging of goods, measuring containers, 
quantities and capacities permitted for pre-packaged 
products, the make-up by weight or volume of prepackaged 
goods, the make-up by volume of prepackaged 
liquids and measuring instruments; and 
(b) adopting and implementing any commitments and 
obligations relating to metrology arising out of or 
under any treaty, convention or other international 
agreement, whether bilateral, regional or multilateral, 
to which Malta is a party. 
(2) The Minister may, on the advice of the Authority, amend 
any of the schedules annexed to this Act; and any such amendments 
may contain such transitional or other incidental provisions as may 
be prescribed. 
Fees. 
Cap. 419. 
20. The Authority may, by virtue of this Act and under the 
powers conferred by article 5 of the Malta Standards Authority Act,

12 CAP. 454.] METROLOGY 
levy fees and other charges for type approval, verification, 
inspection, certification and for any authorisation and registration, 
or in respect of any other matter arising under this Act, and 
different fees or charges may be levied for different classes of cases 
or for different circumstances, and provision may also be made for 
the imposition of additional charges in the event of delay or failure 
to pay such fees. 
Language of 
Schedules and 
regulations. 
21. (1) The Schedules and regulations made under any 
provision of this Act may be drawn up in the English language 
only. 
(2) In the event of conflict or incompatibility between the 
Maltese and English texts of any Schedules and regulations made 
under this Act, the English language version shall prevail. 
PART VI 
Offences and Penalties 
Forgery and false 
marking. 
22. Any person who - 
(a) forges or counterfeits any mark of a type used on any 
measuring instrument used or intended to be used for 
any prescribed purpose; 
(b) applies to any measuring instrument a mark which is 
forged or counterfeit, or which is false or incorrect; or 
(c) uses, sells, utters or disposes of any measuring 
instrument with such forged, counterfeit, false or 
incorrect mark thereon, or any mark liable to be 
confused with marks authorised under the provisions 
of this Act, 
shall be guilty of an offence. 
Tampering with 
marks and 
measuring 
instruments. 
23. Any person who - 
(a) by any means renders a measuring instrument false or 
inaccurate; 
(b) for any prescribed purpose, uses, supplies, sells, utters 
or disposes of a false or inaccurate measuring 
instrument; or 
(c) not being an inspector or verifier authorised under this 
Act, attaches, affixes inscribes, inserts or otherwise 
applies any mark or plate intended for marking, or 
removes, defaces, obliterates or otherwise changes any 
such mark or plate from a measuring instrument, or 
attaches, affixes, inscribes or inserts such mark or 
plate into a measuring instrument other than the 
measuring instrument on which the mark was lawfully 
inscribed in terms of this Act, 
shall be guilty of an offence. 
Removing or 
breaking of tags, 
seals and devices. 
24. Any person who unlawfully removes, defaces, obliterates, 
breaks or otherwise changes any tag, seal or device that has been 
placed, affixed or attached by an inspector or by a verifier to a 
measuring instrument that is or is intended to be used for any

METROLOGY [ CAP. 454. 13 
prescribed purpose shall be guilty of an offence. 
Short measure on 
sale. 
25. Any person who - 
(a) sells any product by weight, measure or number where 
the weight, measure or number of the goods sold is 
less than that purported to be sold or is less than 
corresponds with the price charged; 
(b) in connection with a measuring instrument, makes a 
false record of any measuring; or 
(c) commits any other fraud in connection with any 
measuring by means of a measuring instrument, 
shall be guilty of an offence. 
Prosecution of 
offences. 
26. (1) The Head may assist and participate in the prosecution 
of offences under this Act. 
(2) Proceedings for an offence under this Act may be instituted 
within twelve months from the commission of the offence. 
Penalties. 27. (1) A person found guilty of an offence under articles 
9(7), 22, 23, 24 and 25 shall, on conviction, be liable to a fine 
(multa) of not less than five hundred liri and not exceeding five 
thousand liri, or to imprisonment for a term not exceeding two 
years, or to both such fine and imprisonment. 
(2) A person found guilty of an offence under this Act, other 
than an offence listed in subarticle (1), shall, on conviction, be 
liable to a fine (multa) of not less than fifty liri and not exceeding 
one thousand liri, or to imprisonment for a term not exceeding six 
months, or to both such fine and imprisonment. 
Cap. 9. (3) Without prejudice to the provisions of the Criminal Code, 
in any judgement given in proceedings instituted under this Act, the 
Court may order the forfeiture, destruction or other method of 
disposal of the goods or measuring instruments to which any of the 
offences relates, as it may consider appropriate at the expense of 
the person found guilty of the offence. 
(4) Where it is satisfied that the circumstances so warrant, the 
Court may, upon conviction for any offence committed under this 
Act, additionally order the suspension or cancellation of any 
license or licenses issued in favour of the person charged or in 
respect of the premises involved in the proceedings. 
(5) Any person convicted in relation to an offence under article 
6(6) shall be liable to an additional fine (multa) of not more than 
two hundred liri for each day that the notice has not been complied 
with. 
(6) Where a person has been convicted of an offence under this 
Act, the Court shall order that person to reimburse to the Authority, 
within such period as the Court shall stipulate, any costs incurred in 
connection with the proceedings instituted against him. Such costs 
shall include expenses incurred in the seizure, lifting, detention, 
testing, analysis, inspection and examination of measuring 
instruments and measurement standards involved in the said 
proceedings.

14 CAP. 454.] METROLOGY 
(7) The Attorney General shall have the right to appeal from 
any judgement given in proceedings instituted under this Act or in 
connection with regulations made thereunder. 
PART VII 
Repeals and Savings 
Repeal of previous 
legislation. 
Cap. 39. 
28. (1) The Weights and Measures Ordinance is hereby 
repealed and any references in any other law to that Ordinance shall 
be construed as being references to this Act; provided that any 
registrations, licences, authorisations, orders, regulations or other 
action whatsoever made or issued by virtue of the said Ordinance 
shall continue in force as if made or issued under this Act in so far 
as applicable. 
(2) Unless the context otherwise requires, any reference in any 
other law, contract or other act in force at the commencement of 
this Act to standard weights or measures in use in Malta shall be 
deemed to be references to the respective equivalents ascertained in 
terms of the First and Third Schedules to this Act. 
(3) Verifications issued under the Weights and Measures 
Ordinance which are valid immediately before the coming into 
force of article 8 shall continue to be valid on or after that date for 
such period as may be prescribed by the Directorate by notice 
published in the Gazette.

METROLOGY [ CAP. 454. 15 
FIRST SCHEDULE 
(Article 14) 
LEGAL UNITS OF MEASUREMENT 
1. SI UNITS AND THEIR DECIMAL MULTIPLES AND SUBMULTIPLES 
1.1. SI base units 
Definitions of SI base units: 
Unit of length 
A metre is the length of the path travelled in a vacuum by light during 1/299 792 
458 seconds. 
Unit of mass 
The kilogram is the unit of mass; it is equal to the mass of the international 
prototype of the kilogram. 
Unit of time 
The second is the duration of 9 192 631 770 periods of the radiation corresponding 
to the transition between the two hyperfine levels of the ground state of the caesium 
133 atom. 
Unit of electric current 
The ampere is that constant current which, if maintained in two straight parallel 
conductors of infinite length, of negligible circular cross-article and placed one 
metre apart in a vacuum, would produce between the conductors a force equal to 2 x 
10-7 newton per metre of length. 
Unit of thermodynamic temperature 
The kelvin, unit of thermodynamic, is the fraction 1/273.16 of the thermodynamic 
temperature of the triple point of water. 
Unit of amount of substance 
1. The mole is the amount of substance of a system which contains as many 
elementary entities as there are atoms in 0.012 kg of carbon 12. 
2. When the mole is used, the elementary entities must be specified and may be 
atoms, molecules, ions, electrons, other particles or specified groups of such 
particles. 
Unit of luminous intensity 
The candela is the luminous intensity, in a given direction, of a source which emits 
monochromatic rays with a frequency of 540 x 1012 hertz and whose energy intensity 
in that direction is 1/683 watt per steradian. 
Quantity Unit 
Name Symbol 
Length 
Mass 
Time 
Electric current 
Thermodynamic temperature 
Amount of substance 
Luminous intensity 
metre 
kilogram 
second 
ampere 
kelvin 
mole 
candela 
m
kg 
s
A
K
mol 
cd

16 CAP. 454.] METROLOGY 
1.1.1 Special name and symbol of the SI unit of temperature for expressing 
Celsius temperature 
Celsius temperature t is defined as the difference t = T - T0 between the two 
thermodynamic temperatures T and T0 where T0 = 273,15 K. An interval or 
difference of temperature may be expressed either in kelvins or in degrees Celsius. 
The unit of "degrees Celsius" is equal to the unit "kelvin". 
1.2 Other SI units 
1.2.1 Supplementary SI units 
Definitions of supplementary SI units: 
Unit of plane angle 
The radian is the angle between two radii of a circle cut off on the circumference 
of an arc equal in length to the radius. 
Unit of solid angle 
The steradian is the solid angle of a cone which, having its vertex in the centre of 
a sphere, cuts off on the surface of the sphere an area equal to that of a square with 
sides of length equal to the radius of the sphere. 
1.2.2. Derived SI units 
Units derived coherently from SI base units and supplementary SI units are given 
as algebraic expressions in the form of products of powers of the SI base units and/or 
supplementary SI units with a numerical factor equal to 1. 
1.2.3. Derived SI units having names and symbols 
Quantity Unit 
Name Symbol 
Celsius temperature degree Celsius oC 
Quantity Unit 
Name Symbol 
Plane angle 
Solid angle 
Radian 
Steradian 
rad 
sr 
Quantity Unit Expression 
Name Symbol In other SI 
units 
In terms of base or 
supplementary SI 
units 
Frequency hertz Hz s-1 
Force newton N m . kg . s-2 
Pressure, stress pascal Pa N . m-2 m-1 . kg . s-2 
Energy, work; 
quantity of heat 
joule J N . m m2 . kg . s-2 
Power, radiant flux watt W J . s-1 m2 . kg . s-3 
Quantity of electricity, 
electric charge 
coulomb C s . A 
Electric potential, 
potential difference, 
electromotive force 
volt V W . A-1 m2 . kg . s-3 . A -1 
Electric resistance ohm V . A-1 m2 . kg . s-3 . A -2 
W

METROLOGY [ CAP. 454. 17 
Units derived from SI base units or supplementary units may be expressed in 
terms of the units listed in this Schedule. 
In particular, derived SI units may be expressed by the special names and symbols 
given in the above table; for example, the SI unit of dynamic viscosity may be 
expressed as m-1 . kg . s-1 or N . s . m-2 or Pa . s. 
1.3 Prefixes and their symbols used to designate certain decimal multiples 
and submultiples 
The names and symbols of the decimal multiples and submultiples of the unit of 
mass are formed by attaching prefixes to the word ‘gram’ and their symbols to the 
symbol ‘g’. 
Where a derived unit is expressed as a fraction, its decimal multiples and 
submultiples may be designated by attaching a prefix to units in the numerator or the 
denominator, or in both these parts. 
Compound prefixes, that is to say prefixes formed by the juxtaposition of several 
of the above prefixes, may not be used. 
Conductance siemens S A . V-1 m-2 . kg-1 . s3 . A2 
Capacitance farad F C . V-1 m-2 . kg-1 . s4 . A2 
Magnetic flux weber Wb V . s m2 . kg . s-2 . A -1 
Magnetic flux density tesla T Wb . m-2 kg . s-2 . A -1 
Inductance henry H Wb . A-1 m2 . kg . s-2. A -2 
Luminous flux lumen lm cd . sr 
Illuminance lux lx lm . m-2 m-2 . cd . sr 
Activity 
(of a radionuclide) 
becquerel Bq s-1 
Absorbed dose, specific 
energy imported, kerma, 
absorbed dose index 
gray Gy J . Kg-1 m2 . s-2 
Dose equivalent sievert Sv J . Kg-1 m2 . s-2 
Factor Prefix Symbol Factor Prefix Symbol 
1024 yotta Y 10-1 deci d 
1021 zetta Z 10-2 centi c 
1018 exa E 10-3 milli m 
1015 peta P 10-6 micro m 
1012 tera T 10-9 nano n 
109 giga G 10-12 pico p 
106 mega M 10-15 femto f 
103 kilo k 10-18 atto a 
102 hecto h 10-21 zepto z 
101 deca da 10-24 yocto y’

18 CAP. 454.] METROLOGY 
1.4 Special authorised names and symbols of decimal multiples and 
submultiples of SI units 
Note: The prefixes and their symbols listed in 1.3 may be used in conjunction with 
the units and symbols contained in Table 1.4. 
2. UNITS WHICH ARE DEFINED ON THE BASIS OF SI UNITS BUT ARE 
NOT DECIMAL MULTIPLES OR SUBMULTIPLES THEREOF 
Note: The prefixes listed in 1.3 may only be used in conjunction with the names 
‘grade’ or ‘gon’ and the symbol ‘gon’. 
3. UNITS USED WITH THE SI, WHOSE VALUES IN SI ARE OBTAINED 
EXPERIMENTALLY 
Note: The prefixes and their symbols listed in 1.3 may be used in conjunction with 
these two units and with their symbols. 
4. UNITS AND NAMES OF UNITS PERMITTED IN SPECIALISED FIELDS 
ONLY
Quantity Unit 
Name Symbol Value 
Volume 
Mass 
Pressure, stress 
litre 
tonne 
bar 
l or L 
t
bar 
1 l = 1 dm3 = 10-3 m3 
1 t = 1 Mg = 103 kg 
1 bar = 105 Pa 
Quantity Unit 
Name Symbol Value 
Plane angle revolution 1 revolution = 2 p rad 
grade or gon gon 1 gon = p/200 rad 
degree ° 1° = p/180 rad 
minute of angle ¢ 1¢ = p/10800 rad 
second of angle ² 1² = p/648000 rad 
Time minute min 1 min = 60 s 
hour h 1 h = 3600 s 
day d 1 d = 86400 s 
Quantity Unit 
Name Symbol Definition 
Energy Electronvolt eV The electron volt is the kinetic 
energy acquired by an electron in 
p a s s i n g t h r o u g h a p o t e n t i a l 
difference of 1 volt in vacuum 
Energy Unified atomic mass unit u The unified atomic mass unit 
is equal to 1/12 of the mass of an 
atom of the nuclide 12C. 
Quantity Unit 
Name Symbol Value 
Vergency of optical systems dioptre 1 dioptre = 1 m-1 
Mass of precious stones metric carat 1 metric carat = 2 x 10-4 kg 
Area of farmland and 
building land 
are a 
1 a = 102 m2 
Mass per unit length of textile 
yarns and threads 
tex tex 
1 tex = 10-6 kg . m-1

METROLOGY [ CAP. 454. 19 
Note: The prefixes and their symbols listed in 1.3 may only be used in conjunction 
with the above units and symbols, with the exception of the millimetre of mercury 
and its symbol. The multiple 102 a is, however, called a ‘hectare’. 
5. COMPOUND UNITS 
Combination of the units listed in this Schedule to this Act form compound units. 
SECOND SCHEDULE 
(Article 14) 
MEASURES AND WEIGHTS LAWFUL FOR USE 
FOR THE PURPOSE OF TRADE IN MALTA 
LINEAR MEASURES 
Table I: Measures of - 
SQUARE MEASURES 
Measures of, or of any multiple of, 1 square decimetre. 
CUBIC MEASURES 
1. Measures of, or any multiple of, 0.1 cubic metre. 
2. Measures of any multiple of 10 litres. 
3. Table II: Measures of - 
Blood pressure and pressure 
of other body fluids 
Millimetre of 
mercury 
mm Hg 
1 mm Hg = 133.322 Pa 
Effective cross-sectional area Barn b 1 b = 10 –28 m2 
50 metres 2 metres 
30 metres 1.5 metres 
20 metres 1 metre 
10 metres 0.5 metre 
5 metres 1 decimetre 
3 metres 1 centimetre 
10 litres 100 millilitres 
5 litres 50 millilitres 
2.5 litres 25 millilitres 
2 litres 20 millilitres 
1 litre 10 millilitres 
500 millilitres 5 millilitres 
250 millilitres 2 millilitres 
200 millilitres 1 millilitre

20 CAP. 454.] METROLOGY 
CAPACITY MEASURES 
1. Measures of any multiple of 10 litres 
2. Table III: Measures of - 
WEIGHTS 
1. Table IV: Weights of - 
2. Table V: Weights of - 
10 litres 125 millilitres 
5 litres 100 millilitres 
2.5 litres 50 millilitres 
2 litres 25 millilitres 
1 litre 20 millilitres 
500 millilitres 10 millilitres 
250 millilitres 5 millilitres 
200 millilitres 2 millilitres 
175 millilitres 1 millilitre 
150 millilitres 
25 kilograms 3 grams 
20 kilograms 2 grams 
10 kilograms 1 grams 
5 kilograms 500 milligrams 
2 kilograms 400 milligrams 
1 kilogram 300 milligrams 
500 grams 200 milligrams 
200 grams 150 milligrams 
100 grams 100 milligrams 
50 grams 50 milligrams 
20 grams 20 milligrams 
15 grams 10 milligrams 
10 grams 5 milligrams 
5 grams 2 milligrams 
4 grams 1 milligram 
500 carats (metric) 1 carat (metric) 
200 carats (metric) 0.5 carat (metric) 
100 carats (metric) 0.25 carat (metric) 
50 carats (metric) 0.2 carat (metric) 
20 carats (metric) 0.1 carat (metric) 
10 carats (metric) 0.05 carat (metric) 
5 carats (metric) 0.02 carat (metric) 
2 carats (metric) 0.01 carat (metric)

METROLOGY [ CAP. 454. 21 
THIRD SCHEDULE 
(Article 14) 
GENERAL INFORMATION ON METRIC EQUIVALENTS 
TABLE 
(a) of the values of the principal denominations of measures and weights on the 
metric system expressed by means of denominations of Maltese and Imperial 
measures and weights; and 
(b) of the values of the principal denominations of measures and weights of the 
Maltese and Imperial systems expressed by means of metric weights and measures. 
(a) 
MEASURES OF LENGTH 
MEASURES OF SURFACES 
MEASURES OF CAPACITY FOR LIQUIDS – No. 1 
For Beer, Wine and Spirits 
Metric 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
Miles Yards Feet Inches Decimals Qasab Xbar Decimals 
1 Kilometre - 1093 1 10 113 477 1 70792 
1 Hectometre - 109 1 1 0113 47 5 770792 
1 Decametre - 10 2 9 70113 4 6 1770792 
1 Metre - - 3 3 370113 - 3 81770792 
1 Decimetre - - - 3 9370113 - - 38177079 
1 Centimetre - - - - 39370113 - - 038177079 
1 Millimetre - - - - 039370113 - - 0038177079 
Metric Measures Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
1 Hectare 2.47106 Acres .555988 ta’ Modd 
1 Are 119.60 Square yards .53375 ta’ Sieg] 
1 Square Metre 1.1960 Square yards .053375 ta’ Kejla 
or .22773 ta’ Qasba Kwadra 
1 Square decimetre 15.5 Square inches .14575 ta’ Xiber kwadru 
1 Square centimetre .15500 Square inches .0014575 ta’ Xiber kwadru 
Metric 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
Gallons Quarts Pints Decimals Bramel {arar Kwarti Krate` Decimals 
1 Kilolitre 219 3 1 80 23 0 1 1 15155504 
1 Hectolitre 21 3 1 980 2 1 0 2 490155504 
1 Decalitre 2 0 1 5980 - - 1 4 0490155504 
1 Litre - - 1 75980 - - - - 879901555 
1 Decilitre - - - 175980 - - - - 0879901555 
1 centilitre - - - 0175980 - - - - 00879901555 
1 Millilitre - - - 00175980 - - - - 000879901555

22 CAP. 454.] METROLOGY 
MEASURES OF CAPACITY FOR LIQUIDS – No. 2 
For Oil and Milk 
MEASURES OF CAPACITY FOR DRY GOODS 
CUBIC MEASURES 
WEIGHTS 
Metric 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
Gallons Quarts Pints Decimals Kaffisi Kwarti Krate` Decimals 
1 Kilolitre 219 3 1 80 48 3 2 1347152 
1 Hectolitre 21 3 1 980 4 3 2 21347152 
1 Decalitre 2 0 1 5980 - 1 3 821347152 
1 Litre - - 1 75980 - - - 7821347152 
1 Decilitre - - - 175980 - - - 07821347152 
1 Centilitre - - - 0175980 - - - 007821347152 
1 Millilitre - - - 00175980 - - - 0007821347152 
Metric 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
Qrs. Bushels Gallons Decimals Mdied Tmiem Sieg]an Decimals 
1 Kilolitre 3 3 3 975 3 6 5 58 
1 Hectolitre - 2 5 9975 - 5 2 958 
1 Decalitre - - 2 19975 - - 3 29962464 
1 Litre - - - 219975 - - - 329962464 
1 Decilitre - - - 0219975 - - - 0329962464 
1 Centilitre - - - 00219975 - - - 00329962464 
1 Millilitre - - - 000219975 - - - 000329962464 
Metric Measures Equivalents in Imperial 
Measures 
Equivalents in Maltese 
Measures 
1 Cubic metre 1.307954 Cubic yards 
35.3148 Cubic feet 
55.64278 Xbar kubi 
or 
.1086773 ta’ Qasba kuba 
1 Cubic decimetre 0353148 Cubic feet .0556427 ta’ Xiber kubu 
or 
.0001086773 ta’ Qasba kuba 
1 Cubic centimetre .061024 Cubic inches .0000556427 ta’ Xiber kubu 
Metric 
Weights 
Equivalents in Imperial 
Weights 
Equivalents in Maltese 
Weights 
Cwts. Qrs. Lbs. Decimals Qnatar Irtal Ewieq Decimals 
100 Kilograms 
(1 quintal) 
1 3 24 46223 1 25 29 3525 
Kilogram - - 2 2046223 - 1 7 79352 
1 Hectogram - - - 22046223 - - 3 77935 
1 Decagram - - - 022046223 - - - 377935 
1 Gramme - - - 0022046223 - - - 0377935 
1 Decigram - - - 00022046223 - - - 00377935 
1 Centigram - - - 000022046223 - - - 000377935 
1 Milligram - - - 0000022046223 - - - 0000377935

METROLOGY [ CAP. 454. 23 
(b) 
MEASURES OF LENGTH 
MEASURES OF SURFACE 
MEASURES OF CAPACITY FOR LIQUIDS – No. 1 
For Beer, Wine and Spirits 
Maltese 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in Metric 
Measures 
Feet Inches Decimals Metres Decimal 
1 Qasba 
(8 ixbar) 
6 10 50 2 09549817 
1 Xiber - 10 3125 26193727 
1 Pulzier - - 859375 - 021828105 
1 Mil 5280 equal to yds. 1760 1609 
or 
kilometres 
334 
1.6093 
Maltese 
Measures 
Equivalents in Imperial 
Measures 
Equivalents in metric 
Measures 
Acres Roods Poles Sqr. 
Yards 
Sqr. 
Feet 
Decimals 
1 Modd 4 1 31 3 3 249 1.798599928 hectares 
1 Tomna - 1 4 13 3 9 11.2412495 acres 
1 Sieg] - - 7 12 2 916 187.35416 Sqr. Metres 
1 Kejla - - - 22 3 6 18.735416 Sqr. Metres 
1 Qasba kwadra - - - 5 2 265625 4.3911126 Sqr. Metres 
1 Xiber kwadru - - - - - 7385162 6.8611 Sqr. Decimetres 
Maltese Measures Equivalents in Imperial 
Measures 
Equivalents in metric 
Measures 
Gallons Decimals Litres Decimals 
1 Barmil (4 [arar) 9 50 43 18664945 
1 {arra (2 kwarti) 2 375 10 7966623625 
1 Kwarta (3/4 Krate`) 1 1875 5 39833118125 
1 Karto`` (2 infas) - 2500 1 13649077500 
1 Nofs (2 terzi) - 1250 - 56824538750 
1 Terz (2 pinet) - 0625 - 28412269375 
1 Pinta - 03125 - 142061346875

24 CAP. 454.] METROLOGY 
MEASURES OF CAPACITY FOR LIQUIDS – No. 2 
For Oil and Milk 
MEASURES OF CAPACITY FOR DRY GOODS 
CUBIC MEASURES 
WEIGHTS 
Maltese Measures Equivalents in Imperial 
Measures 
Equivalents in metric 
Measures 
Gallons Decimals Litres Decimals 
1 Qafiz (4 kwarti) 4 50 20 45683395 
1 Kwarta (3/4 Krate`) 1 125 5 1142084875 
1 Karto`` (2 infas) - 28125 1 278552121875 
1 Nofs (2 terzi) - 140625 - 6392760609375 
1 Terz (2a kejliet) - 0703125 - 31963803046875 
1 Kejla (4 kwartini) - 028125 - 1278552121875 
1 Kwartin - 00703125 - 031963803046875 
Maltese Measures Equivalents in Imperial 
Measures 
Equivalents in Metric 
Measures 
Quarters Decimals Hectolitres Decimals 
1 Modd (16-il tomna) 1 - 2 90942 
1 Tomna (6 sieg]an) - 0625 - 18183875 
1 Sieg] (10 kejliet) - 010416 - 03030645 
1 Kejla (10 lumini) - 0010416 - 003030645 
1 Lumin - 00010416 - 0003030645 
Maltese Measures Equivalents in Imperial 
Measures 
Equivalents in Metric 
Measures 
1 Qasab kubu 324.9511 Cubic feet 9.201556 Cubic metres 
1 Xiber kubu .63467 Cubic feet 17.9717 Cubic decimetres 
1 Pulzier kubu .63467 Cubic inches 10.4 Cubic centimetres 
Maltese Measures Equivalents in Imperial 
Measures 
Equivalents in metric 
Measures 
Lbs. Decimals Kilograms Decimals 
1 Qantar or `ental (20 wi\na) 175 - 79 37867525 
1 Wi\na (5 irtal) 8 75 3 9689337625 
1 Ratal (30 Maltese uqija) 1 75 - 7937867525 
1 Uqija (4 Kwarti) - 0583333 - 026459558416 
1 Kwart (2 ottavi) - 01458333 - 00661489604 
1 Ottav - 007291666 - 003307444802 
1 Pe\ata (3 qnatar) 525 - 238 13602575 
1 Ton (weight) 1280 (ratal) 2240 - 1016 -

METROLOGY [ CAP. 454. 25 
FOURTH SCHEDULE 
(Article 14) 
NAMES AND SYMBOLS USED IN 
THE INTERNATIONAL SYSTEM OF UNITS "SI" 
1. Definition 
"SI" shall have the meaning assigned to it in article 2 of the Act. 
2. SI unit symbols 
SI unit symbols (and also many non-SI unit symbols) are written as follows: 
2.1. Roman (upright) type is used for the unit symbols. In general, unit symbols 
are written in lower case, but, if the name of the unit is derived from the proper name 
of a person, the first letter of the symbol is a capital. When the name of a unit is 
spelled out, it is always written in lower case, except when the name is the first word 
of a sentence or is the name "degree Celsius". 
2.2. Unit symbols are unaltered in the plural. 
2.3. Unit symbols are not followed by a full stop (period), except as normal 
punctuation at the end of a sentence. 
3. Algebra of SI unit symbols 
In accord with the general principles adopted by ISO/TC 12 (ISO 31), the 
CIPM recommends that algebraic expressions involving SI unit symbols be 
expressed in standard forms. 
3.1. Half-high dots or spaces are used to express a derived unit formed from two 
or more other units by multiplication. 
Example: N · m or N m. 
3.2 A solidus (oblique stroke, /), a horizontal line, or a negative exponent is 
used to express a derived unit formed from two other units by division. 
Example: m/s or m - s or m · s-1. 
3.3. The solidus is not followed by a multiplication sign or by a division sign on 
the same line unless ambiguity is avoided by parentheses. In complicated cases, 
negative exponents or parentheses are used to avoid ambiguity. 
Examples: m/s2 or m · s-2 but not m/s/s 
m · kg/(s3 · A) or m · kg · s-3 · A -1 but neither m · kg/s3 /A 
nor m · kg/s3 · A. 
4. Rules for using SI prefixes 
In accord with the general principles adopted by the ISO (ISO 31), the CIPM 
recommends that the following rules be observed when using the SI prefixes: 
4.1. Prefix symbols are printed in roman (upright) type with no space between 
the prefix symbol and the unit symbol. 
4.2. The grouping formed by the prefix symbol attached to the unit symbol 
constitutes a new inseparable symbol (of a multiple or submultiple of the unit 
concerned) which can be raised to a positive or negative power and combined with 
other unit symbols to form compound unit symbols. 
Examples:

26 CAP. 454.] METROLOGY 
1 c m3 = (10-2 m )3 = 10-6 m3 
1 µ s-1 = (10-6 s )-1 = 106 s-1 
1 V/cm = (1 V) / (10-2 m) = 102 V / m 
1 cm-1 = (10-2 m)-1 = 102 m-1. 
4.3. Compound prefixes, i.e. prefixes formed by the juxtaposition of two or more 
SI prefixes, are not used. 
Example: 1 nm but not 1 mµm. 
4.4. A prefix is never used in isolation. 
Example: 106 /m3 but not M/m3.

