01980L0181 — EN — 13.06.2020 — 005.001

This text is meant purely as a documentation tool and has no legal effect. The Union's institutions do not assume any liability for its contents. The authentic versions of the relevant acts, including their preambles, are those published in the Official Journal of the European Union and available in EUR-Lex. Those official texts are directly accessible through the links embedded in this document

►B COUNCIL DIRECTIVE of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC (80/181/EEC) (OJ L 039 15.2.1980, p. 40)

Amended by:





Corrected by:









▼B

COUNCIL DIRECTIVE

of 20 December 1979

on the approximation of the laws of the Member States relating to units of measurement and on the repeal of Directive 71/354/EEC

(80/181/EEC)







Article 1

The legal units of measurement within the meaning of this Directive which must be used for expressing quantities shall be:

(a) those listed in Chapter I of the Annex;

▼M4

(b) those listed in Chapter II of the Annex only in those Member States where they were authorised on 21 April 1973;

▼M2

(c) those listed in Chapter III of the Annex only in those Member States where they were authorized on 21 April 1973 and until a date to be fixed by those States. This date may not be later than 31 December 1994;

(d) those listed in Chapter IV of the Annex only in those Member States where they were authorized on 21 April 1973 and until a date to be fixed by those States. This date may not be later than 31 December 1999.

▼B

Article 2

▼M4

(a) The obligations arising under Article 1 relate to measuring instruments used, measurements made and indications of quantity expressed in units of measurement.

▼B

(b) This Directive shall not affect the use in the field of air and sea transport and rail traffic of units, other than those made compulsory by the Directive, which have been laid down in international conventions or agreements binding the Community or the Member States.

Article 3

1. For the purposes of this Directive ‘supplementary indication’means one or more indications of quantity expressed in units of measurement not contained in Chapter I of the Annex accompanying an indication of quantity expressed in a unit contained in that Chapter.

▼M4

2. The use of supplementary indications shall be authorised.

▼B

3. However, Member States may require that measuring instruments bear indications of quantity in a single legal unit of measurement.

4. The indication expressed in a unit of measurement listed in Chapter I shall predominate. In particular, the indications expressed in units of measurement not listed in Chapter I shall be expressed in characters no larger than those of the corresponding indication in units listed in Chapter I.

▼M2 —————

▼B

Article 4

The use of units of measurement which are not or are no longer legal shall be authorized for:

— products and equipment already on the market and/or in service on the date on which this Directive is adopted,

— components and parts of products and of equipment necessary to supplement or replace components or parts of the above products and equipment.

However, the use of legal units of measurement may be required for the indicators of measuring instruments.

Article 5

International standard ISO 2955 of ►M2 15 May 1983 ◄ , ‘Information processing — Representations of SI and other units for use in systems with limited character sets’ shall apply in the field covered by paragraph 1 thereof.

Article 6

Directive 71/354/EEC shall be repealed on 1 October 1981.

▼M2 —————

▼M3

Article 6a

Issues concerning the implementation of this Directive and, in particular, the matter of supplementary indications shall be further examined, and if necessary the appropriate measures adopted in accordance with the procedure referred to in Article 18 of Council Directive 71/316/EEC ( 1 ).

▼M4

Article 6b

The Commission shall monitor market developments relating to this Directive and its implementation with regard to the smooth functioning of the internal market and international trade and shall submit a report on those developments, accompanied by proposals where appropriate, to the European Parliament and to the Council by 31 December 2019.

▼B

Article 7

(a) Member States shall adopt and publish before 1 July 1981 the laws, regulations and administrative provisions necessary to comply with this Directive and shall inform the Commission thereof. They shall apply these provisions from 1 October 1981.

(b) As from the date of notification of this Directive, Member States shall also ensure that the Commission is informed, in sufficient time to enable it to submit its comments, of any draft laws, regulations or administrative provisions which they intend to adopt in the field covered by this Directive.

Article 8

This Directive is addressed to the Member States.









▼C1

ANNEX

CHAPTER I

LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (a)

1. SI UNITS AND THEIR DECIMAL MULTIPLES AND SUBMULTIPLES

▼M5

1.1. SI base units







Quantity Unit Name Symbol Time second s Length metre m Mass kilogram kg Electric current ampere A Thermodynamic temperature kelvin K Amount of substance mole mol Luminous intensity candela cd

Definitions of SI base units:

Unit of time

The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency Δ ν Cs , the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s –1 .

Unit of length

The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m/s, where the second is defined in terms of Δ ν Cs .

Unit of mass

The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6,626 070 15 × 10 –34 when expressed in the unit J s, which is equal to kg m 2 s –1 , where the metre and the second are defined in terms of c and Δ ν Cs .

Unit of electric current

The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1,602 176 634 × 10 –19 when expressed in the unit C, which is equal to A s, where the second is defined in terms of Δ ν Cs .

Unit of thermodynamic temperature

The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1,380 649 × 10 –23 when expressed in the unit J K –1 , which is equal to kg m 2 s –2 K –1 , where the kilogram, metre and second are defined in terms of h , c and Δ ν Cs .

Unit of amount of substance

The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6,022 140 76 × 10 23 elementary entities. This number is the fixed numerical value of the Avogadro constant, N A, when expressed in the unit mol –1 and is called the Avogadro number.

The amount of substance, symbol n , of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.

Unit of luminous intensity

The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540 × 10 12 Hz, K cd , to be 683 when expressed in the unit lm W –1 , which is equal to cd sr W –1 , or cd sr kg –1 m –2 s 3 , where the kilogram, metre and second are defined in terms of h , c and Δ ν Cs .

1.1.1. Special name and symbol of the SI derived unit of temperature for expressing Celsius temperature







Quantity Unit Name Symbol Celsius temperature degree Celsius °C

Celsius temperature t is defined as the difference t = T – T0 between the two thermodynamic temperatures T and T 0 where T 0 = 273,15 K. An interval or difference of temperature may be expressed either in kelvins or in degrees Celsius. The unit ‘degree Celsius’ is equal to the unit ‘kelvin’.

▼M4

1.2. SI derived units

▼M4 —————

▼M4

1.2.2. General rule for SI derived units

Units derived coherently from SI base units are given as algebraic expressions in the form of products of powers of the SI base units with a numerical factor equal to 1.

1.2.3. SI derived units with special names and symbols







Quantity Unit Expression Name Symbol In terms of other SI units In terms of SI base units Plane angle radian rad m · m–1 Solid angle steradian sr m2 · m–2 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 (1), 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 Ω V · A–1 m2 · kg · s–3 · A–2 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 cd Illuminance lux lx lm · m–2 m–2 · cd Activity (of a radionuclide) becquerel Bq s–1 Absorbed dose, specific energy imparted, kerma, absorbed dose index gray Gy J · kg–1 m2 · s–2 Dose equivalent sievert Sv J · kg–1 m2 · s–2 Catalytic activity katal kat mol · s–1 (1) Special names for the unit of power: the name volt–ampere (symbol ‘VA’) when it is used to express the apparent power of alternating electric current, and var (symbol ‘var’) when it is used to express reactive electric power. The ‘var’ is not included in GCPM resolutions.

Units derived from SI base units may be expressed in terms of the units listed in Chapter I.

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.

▼C1

1.3. Prefixes and their symbols used to designate certain decimal multiples and submultiples

▼M3







Factor Prefix Symbol 1024 yotta Y 1021 zetta Z 1018 exa E 1015 peta P 1012 tera T 109 giga G 106 mega M 103 kilo ►C2 k ◄ 102 hecto ►C2 h ◄ 101 deca da 10-1 deci d 10-2 centi c 10-3 milli m 10-6 micro μ 10-9 nano n 10-12 pico p 10-15 femto f 10-18 atto a 10-21 zepto z 10-24 yocto y

▼C1

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.

1.4. Special authorized names and symbols of decimal multiples and submultiples of SI units







Quantity Unit Name Symbol Value Volume litre 1 or L (1) 1 l = 1 dm3 = 10-3 m3 Mass tonne t 1 t = 1 Mg = 103 kg Pressure, stress bar bar (2) 1 bar = 105 Pa (1) The two symbols ‘I’and ‘L’ may be used for the litre unit. (2) Unit listed in the International Bureau of Weights and Measures booklet as among the units to be permitted temporarily.

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







Quantity Unit Name Symbol Value Plane angle revolution* (1) () 1 revolution = 2 π rad grade* or gon* gon* degree ° minute of angle ′ second of angle ″ Time minute min 1 min = 60 s hour h 1 h = 3 600 s day d 1 d = 86 400 s (1) The character (*) after a unit name or symbol indicates that it does not appear in the lists drawn up by the CGPM, CIPM o BIPM. This applies to the whole of this Annex. (2) No international symbol exists.

Note:

The prefixes listed in 1.3 may only be used in conjunction with the names ‘grade’ or ‘gon’ and the symbol ‘gon’.

▼M3

3. UNITS USED WITH THE SI, WHOSE VALUES IN SI ARE OBTAINED EXPERIMENTALLY







Quantity Unit Name Symbol Definition Energy Electronvolt eV The electron volt is the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in vaccum Mass Unified atomic mass unit u The unified atomic mass units is equal to 1/12 of the mass of an atom of the nuclide 12C.

Note:

The prefixes and their symbols listed in 1.3 may be used in conjunction with these two units and with their symbols.

▼C1

4. UNITS AND NAMES OF UNITS PERMITTED IN SPECIALIZED FIELDS ONLY







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 × 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 ▼M1 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 ▼C1

Note:

►M1 The prefixes and their symbols listed in 1.3 may be used in conjunction with the above units and symbols, with the exception of the millimetre of mercury and its symbol. The multiple of 102a is, however, called a ‘hectare’. ◄

5. COMPOUND UNITS

Combinations of the units listed in Chapter I form compound units.

▼M2

CHAPTER II

LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (b), PERMITTED FOR SPECIFIC USES ONLY







Field of application Unit Name Approximate value Symbol Road traffic signs, distance and speed measurement mile 1 mile = 1 609 m mile yard 1 yd = 0,9144 m yd foot 1 ft = 0,3048 m ft inch 1 in = 2,54 × 10-2 m in Dispense of draught beer and cider; milk in returnable containers pint 1 pt = 0,5683 × 10-3 m3 pt ▼M4 ————— ▼M2 Transaction in precious metals troy ounce 1 oz tr = 31,10 × 10-3 kg oz tr

▼M4

The units listed in this Chapter may be combined with each other or with those in Chapter I to form compound units.

▼C1

CHAPTER III

LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (c)







QUANTITIES, NAMES OF UNITS, SYMBOLS AND APPROXIMATE VALUES ▼M2 ————— ▼C1 Length inch 1 in = 2·54 × 10-2 m foot 1 ft = 0·3048 m ▼M2 ————— ▼C1 mile 1 mile = 1 609 m yard 1 yard = 0·9144 m Area square foot 1 sq ft = 0·929 × 10-1 m2 acre 1 ac = 4 047 m2 square yard 1 sq yd = 0·8361 m2 Volume fluid ounce 1 fl oz = 28·41 × 10-6 m3 gill 1 gill = 0·1421 × 10-3 m3 pint 1 pt = 0·5683 × 10-3 m3 quart 1 qt = 1·137 × 10-3 m3 gallon 1 gal = 4·546 × 10-3 m3 Mass ounce (avoirdupois) 1 oz = 28·35 × 10-3 kg troy ounce 1 oz tr = 31·10 × 10-3 kg pound 1 lb = 0·4536 kg Energy therm 1 therm = 105·506 × 106 J

Until the date to be fixed under Article 1 (c), the units listed in Chapter III may be combined with each other or with those in Chapter I to form compound units.

▼M2

CHAPTER IV

LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE I (d), PERMITTED IN SPECIALIZED FIELDS ONLY







Field of application Unit Name Approximate value Symbol Marine navigation fathom 1 fm = 1,829 m fm Beer, cider, waters, lemonades and fruit juices in returnable containers pint 1 pt = 0,5683 × 10-3 m3 pt fluid ounce 1 fl oz = 28,41 × 10-6 m3 fl. oz Spirit drinks gill 1 gill = 0,142 × 10-3 m3 gill Goods sold loose in bulk ounce (avoir dupois) 1 oz = 28,35 × 10-3 kg oz pound 1 lb = 0,4536 kg lb Gas supply therm 1 therm = 105,506 × 106 J therm

Until the date to be fixed under Article 1 (d), the units listed in this Chapter may be combined with each other or with those in Chapter I to form compound units.