17.7.91 Official Journal of the European Communities NoC 185/13 
Proposal for a Council Directive on [the approximation of the laws of the Member States 
relating to] units of measurement 
(91/C 185/06) 
SEC(91) 1047 final 
(Submitted by the Commission on 21 June 1991) 
THE COUNCIL OF THE EUROPEAN COMMUNITIES, 
Having regard to the Treaty establishing the European 
Economic Community, and in particular Article 100a 
thereof, 
Having regard to the proposal from the Commission, 
In cooperation with the European Parliament, 
Having regard to the opinion of the Economic and 
Social Committee, 
Whereas Council Directive 80/181/EEC 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 ('), as last amended 
by Directive 89/617/EEC (2), has been substantially 
amended; whereas for reasons of clarity and rationality 
the said Directive should be consolidated; 
Whereas units of measurement are essential in the use of 
all measuring instruments, to express measurements or 
any indication of quantity; whereas units of 
measurement are used in most fields of human activity; 
whereas it is necessary to ensure the greatest possible 
clarity in their use; whereas it is therefore necessary to 
make rules for their use within the Community for 
economic, public health, public safety or administrative 
purposes; 
Whereas, however, there exist international conventions 
or agreements in the field of international transport 
which bind the Community or the Member States; 
whereas these conventions or agreements have to be 
respected; 
Whereas the laws which regulate the use of units of 
measurement in the Member States differ from one 
Member State to another and as a result hinder trade; 
whereas, in these circumstances, it is necessary to 
harmonize laws, regulations and administrative 
provisions in order to overcome such obstacles; 
Whereas units of measurement are the subject of interna­
tional resolutions adopted by the General Conference of 
Weights and Measures (CGPM) set up by the Metre 
Convention signed in Paris on 20 May 1875, to which all 
(') OJ No L 39, 15. 2. 1980, p. 40. 
O OJ No L 357, 7. 12. 1989, p. 28. the Member States adhere; whereas the 'International 
System of Units' (SI) was drawn up as a result of these 
resolutions; 
Whereas it is necessary, in order to avoid serious diffi­
culties, to provide for a transitional period during which 
units of measurement which are not compatible with the 
international system can be phased out; whereas it is 
nevertheless essential to allow the Member States 
wishing to do so to bring into force as quickly as 
possible, on their territory, the provisions of Chapter 1 
of Annex I; whereas it is therefore necessary to limit the 
duration of this transitional period at Community level 
while, at the same time, leaving the Member States free 
to curtail that period; 
Whereas, during the transitional period, it is essential, 
particularly in order to protect the consumer, to 
maintain a clear position on the use of units of 
measurement in trade between the Member States; 
whereas the obligation on the Member States to allow 
use of supplementary indications on products and 
equipment imported from other Member States during 
this transitional period seems to serve this purpose well; 
Whereas the systematic adoption of a solution of this 
kind for all measuring instruments, including medical 
instruments, is however not necessarily desirable; 
whereas the Member States should therefore be able to 
require that, on their territory, measuring instruments 
bear indications of quantity in a single legal unit of 
measurement; 
Whereas this Directive does not affect the continued 
manufacture of products already on the market; whereas 
it does, however, affect the placing on the market and 
use of products and equipment bearing indications of 
quantity in units of measurement which are no longer 
legal units of measurement, when such products and 
equipment are necessary to supplement or replace 
components or parts of such products, equipment and 
instruments already on the market; whereas it is 
therefore necessary for Member States to authorize the 
placing on the market and the use of such products and 
equipment to complete and replace components, even 
when they bear indications of quantity in units of 
measurement which are no longer legal units of 
measurement, so that products, equipment or instruments 
already on the market may continue to be used; 
Whereas the International Organization for Standardiz­
ation (ISO) on 15 May 1983 adopted an international 
standard on the representation of SI and other units for 
use in systems with limited sets of characters; whereas it 
is advisable for the Community to adopt the solutions 
which have already been approved on a wider inter­
national level by ISO Standard 2955 of 15 May 1983; 
NoC 185/14 Official Journal of the European Communities 17.7.91 
Whereas in a recommendation of 22 May 1981 the 
World Health Organization requested that the 
millimetre of mercury be retained in addition to the kilo-
pascal as a unit for the measurement of the pressure of 
blood and other body fluids; whereas it is advisable for 
the Community to adopt this solution; 
Whereas the barn is the unit universally used to measure 
the effective cross-sectional area on the occasion of 
nuclear reactions; whereas experience has shown that 
this specific unit could not easily be replaced by an SI 
unit; whereas it is therefore necessary to authorize its use 
in the nuclear field; 
Whereas this Directive must not affect the obligations on 
the Member States arising from Directives 80/181 /EEC, 
85/1/EECO) and 89/617/EEC, 
HAS ADOPTED THIS DIRECTIVE: 
Article 1 
The legal units of measurement within the meaning of 
this Directive which must be used for expressing quan­
tities shall be those contained in Annex I: 
(a) those listed in Chapter 1; 
(b) those listed in Chapter 2 only in those Member 
States where they were authorized on 21 April 1973 
and until a date to be fixed by those States; 
(c) those listed in Chapter 3 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 4 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. 
Article 2 
(a) The obligations arising pursuant to Article 1 relate to 
measuring instruments used, measurements made and 
indications of quantity expressed in units of 
measurement, for economic, public health, public 
safety or administrative purposes. 
(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 1 of Annex I accompanying an indication of 
quantity expressed in a unit contained in that Chapter. 
2. The use of supplementary indications shall be auth­
orized until 31 December 1999. 
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 1 shall predominate. In particular, the 
indications expressed in units of measurement not listed 
in Chapter 1 shall be expressed in characters no larger 
than those of the corresponding indication in units listed 
in Chapter 1 of Annex I. 
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 15 May 1983 'Infor­
mation 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 
The Directives listed in Annex II are hereby repealed, 
without prejudice to the obligations of the Member 
States concerning the implementation of the said 
Directives. 
References to the said Directives shall be construed as 
references to this Directive. 
Article 7 
(') OJ No L 2, 3. 1. 1985, p. 11. This Directive is addressed to the Member States. 
17.7.91 Official Journal of the European Communities NoC 185/15 
ANNEX I 
CHAPTER 1 
LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (a) 
1. SI UNITS AND THEIR DECIMAL MULTIPLES AND SUBMULTIPLES 
1.1. SI base units 
Quantity 
Length 
Mass 
Time 
Electric current 
Thermodynamic temperature 
Amount of substance 
Luminous intensity Unit 
Name 
metre 
kilogram 
second 
ampere 
kelvin 
mole 
candela Symbol 
m 
kg 
s 
A 
K 
mol 
cd 
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. 
(Seventeenth CGPM (1983), resolution 1). 
Unit of mass 
The kilogram is the unit of mass; it is equal to the mass of the international prototype of the 
kilogram. 
(Third CGPM (1901), page 70 of the conference report). 
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. 
(Thirteenth CGPM (1967), resolution 1). 
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-section and placed one metre apart in a vacuum, would 
produce between the conductors a force equal to 2 x 10"7 ton per metre of length. 
(CIPM (1946), resolution 2, approved by the ninth CGPM (1948)). 
Unit of thermodynamic temperature 
The kelvin, unit of thermodynamic temperature, is the fraction 1/273,16 of the thermodynamic 
temperature of the triple point of water. 
(Thirteenth CGPM (1967), resolution 4). 
No C 185/16 Official Journal of the European Communities 17. 7. 91 
Unit of amount of substance 
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. 
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 partides. 
(Fourteenth CGPM (1971), resolution 3). 
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 10" hertz and whose energy intensity in that direction is 1/683 
watt per steradian. 
(Sixteenth CGPM (1979), resolution 3). 
1.1.1. Special name and symbol of the SI unit of temperature for expressing Celsius temperature 
Quantity 
Celsius temperature Unit 
Name 
degree Celsius Symbol 
°C 
Celsius temperature t is defined as the difference t = T — T0 between the two thermodynamic 
temperatures T and T0 where T0 = 273,15 kelvins. An interval of or difference in temperature may be 
expressed either in kelvins or in degrees Celsius. The unit of 'degree Celsius' is equal to the unit 'kelvin'. 
1.2. Other SI units 
1.2.1. Supplementary SI units 
Quantity 
Plane angle 
Solid angle Units 
Name 
radian 
steradian Symbol 
rad 
sr 
(Eleventh CGPM, 1960, resolution 12). 
Definitions of supplementary SI units: 
Plane angle unit 
The radian is the plane angle between two radii which, on the circumference of a circle, cut 
an arc equal in length to the radius. 
(International standard ISO 31 — I, December 1965). 
Solid angle unit 
The steradian is the solid angle which has its apex at the centre of a sphere and which 
describes on the surface of the sphere an area equal to that of a square having as its side the 
radius of the sphere. 
(International standard ISO 31 — I, December 1965). 
17. 7. 91 Official Journal of the European Communities No C 185/17 
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 
Frequency 
Force 
Pressure, stress 
Energy, work; quantity of heat 
Power (l), radiant flux 
Quantity of electricity, electric 
charge 
Electric potential, potential 
difference, electromotive force 
Electric resistance 
Conductance 
Capacitance 
Magnetic flux 
Magnetic flux density 
Inductance 
Luminous flux 
Illuminance 
Activity 
(of a radionuclid) 
Absorbed dose, specific energy 
imported, kerma, absorbed 
dose index 
Dose equivalent Units 
Name 
hertz 
newton 
pascal 
joule 
watt 
coulomb 
volt 
ohm 
Siemens 
farad 
weber 
tesla 
henry 
lumen 
lux 
becquerel 
gray 
sievert Symbol 
Hz 
N 
Pa 
J 
W 
C 
V 
Q 
S 
F 
Wb 
T 
H 
lm 
lx 
Bq 
Gy 
Sv Expression 
In other 
SI units 
N • m-2 
N- m 
J-s-1 
W-A-1 
V • A"1 
A-V-1 
c • v-1 
V- s 
Wb • m"2 
Wb • A"1 
lm • m'2 
J kg"1 
J • kg-In terms of base 
or supplementary 
SI units 
S"1 
m • kg • s-2 
m_1 • kg • s-2 
m2 • kg • s"2 
m2 • kg • s_J 
s • A 
m2 • kg • s-5 • A"1 
m2 • kg • s-5 • A-2 
m-2 • kg"1 • s> • A2 
m"2 • kg"1 • s4 • A2 
m2 • kg • s"2 • A-1 
kg • s-2 • A"1 
m2 • kg • s-2 • A-2 
cd • sr 
m"2 • cd • sr 
S"1 
m2 • s-2 
m2 • s"* 
(') Special names for the units of power: the name volt ampere (symbol "VA') when it is used to express 
the apparent power of alternaung electric current, and var (symbol 'var'), when it is used to express 
reactive electric power. The 'var' is not included in CGPM resolutions. 
Units derived from SI base units or supplementary units may be expressed in terms of the 
units listed in Chapter 1. 
In particular, derived SI units may be expressed by the special names and symbols given in 
the above tables; for example, the SI unit of dynamic viscosity may be expressed as 
m'1 • kg • s"1 of N • s • nr2 of Pa • s. 
1.3. Prefixes and their symbols used to designate certain decimal multiples and submultiples 
Factor 
10" 
10,s 
1012 
10' 
104 
105 
102 
101 Prefix 
exa 
peta 
tera 
giga 
mega 
kilo 
hecto 
deca Symbol 
E 
P 
T 
G 
M 
k 
h 
da Factor 
lO"1 
io-2 
io-s 
io-* 
io-' 
io-12 
io-ii 
io-" Prefix 
deci 
centi 
milli 
micro 
nano 
pico 
femto 
atto Symbol 
d 
c 
m 
V-
n 
P 
f 
a 
NoC 185/18 Official Journal of the European Communities 17.7.91 
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 it 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 
Volume 
Mass 
Pressure, stress Unit 
Name 
litre 
tonne 
bar Symbol 
1 or L (») 
t 
bar(J) Value 
1 1 = 1 dm3 - 10-3 m5 
1 t = 1 Mg = 103 kg 
1 bar = 10s Pa 
(') The two symbols T and 'L' may be used for the litre unit. 
(Sixteenth CGPM (1979), resolution 5). 
(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 
Plane angle 
Time Unit 
Name 
revolution * (') (a) 
grade * or gon * 
degree 
minute of angle 
second of angle 
minute 
hour 
day Symbol 
gon* 
° 
' 
* 
min 
h 
d Value 
1 revolution = 2 n rad 
1 n A 1 gon = — rad 
10 = ifo rad 
1 " 10 800 rad 
1 ~ 648 000 fad 
1 min = 60 s 
1 h = 3 600 s 
1 d = 86 400 s 
(') The character (") after a unit name or symbol indicates that it does not appear in the lists drawn up by the CGPM, 
CIPM or BIPM. This applies to the whole of this Annex. 
(a) 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'. 
17.7.91 Official Journal of the European Communities NoC 185/19 
3. UNITS DEFINED INDEPENDENTLY OF THE SEVEN SI BASE UNITS 
The unified atomic mass unit is one-twelfth of the mass of an atom of the nuclide 12C. 
The electronvolt is the kinetic energy acquired by an electron passing in a vacuum from one point to 
another whose potential is one volt higher. 
Quantity 
Mass 
Energy Unit 
Name 
unifed automic mass unit 
electronvolt Symbol 
u 
eV Value 
1 u * 1,660 565 5 x 10"27 kg 
1 eV « 1,602 189 2 x 10"" J 
The value of these units, expressed in SI units, is not known exactly. 
The above values are taken from CODATA Bulletin No 11 of December 1973 of the International 
Council of Scientific Unions. 
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 SPECIALIZED FIELDS ONLY 
Quantity 
Vergency of optical systems 
Mass of precious stones 
Area of farmland and building 
land 
Mass per unit length of textile 
yarns and threads 
Blood pressure and pressure 
of other body fluids 
Effective cross-sectional area Name 
dioptre * (') 
metric carat 
are 
tex * 
Millimetre of 
mercury 
Barn Unit 
Symbol 
a 
tex * 
mm Hg (*) 
b Value 
1 dioptre = 1 m"1 
1 metric carat = 2 x 10"4 kg 
1 a = 102 m2 
1 tex = 10"' kg-m"1 
1 mm Hg = 133,322 Pa 
1 b = 10 -' m2 
(') The character (*) after a unit name or symbol indicates that it does not appear in the lists drawn up by the CGPM, 
CIPM or BIPM. This applies to the whole of this Annex. 
Note: 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 1 form compound units. 
No C 185/20 Official Journal of the European Communities 17. 7. 91 
CHAPTER 2 
LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (b), PERMITTED FOR 
SPECIFIC USES ONLY 
Field of application 
Road traffic signs, distance and 
speed measurement 
Dispense of draught beer and 
cider; milk • in returnable 
containers 
Land registration 
Transaction in precious metals Name 
mile 
yard 
foot 
inch 
pint 
acre 
troy ounce App 
1 mile = 
1 yd = 
1 ft -
1 in -
lpt = 
1 ac = 
1 oz tr = Unit 
roximate value 
1609 m 
0,9144 m 
0,3048 m 
2,54 x 10"2m 
0,5683 x 10-3mJ 
4 047 m2 
31,10 x 10"J kg Symbol 
mile 
yd 
ft 
in 
Pt 
ac 
oz tr 
Until the date to be fixed under Article 1 (b), the units listed in this Chapter may be combined with each 
other or with those in Chapter 1 to form compound units. ' 
CHAPTER 3 
LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE 1 (c) 
QUANTITIES, NAMES OF UNITS, SYMBOLS AND APPROXIMATE VALUES 
Length 
inch 
foot 
mile 
yard 
Area 
square foot 
acre 
square yard 
Volume 
fluid ounce 
gill 
pint 
quart 
gallon 
Mass 
ounce (avoirdupois) 
troy ounce 
pound 
Energy 
therm 1 in 
1 ft 
1 mile 
1 yard 
1 sq ft 
1 ac 
1 sq yd 
1 fl oz 
1 gill 
1 pt 
1 qt 
1 gal 
1 oz 
1 oz tr 
1 lb 
1 therm = 
= 
= 
= 
= 
= 
= 
-
-
= 
= 
= 
= 
« 
= 
= 2,54 x 10-1 m 
0,3048 m 
1 609 m 
0,9144 m 
0,929 x 10"1 m2 
4 047 m2 
0,8361 m2 
28,41 x 10-' m3 
0,1421 x lO"5 mJ 
0,5683 x 10"J m3 
1,137 x lO"3 mJ 
4,546 x lO"5 m3 
28,35 x lO"3 kg 
31,10 x 10-3 kg 
0,4536 kg 
105,506 x 10* J 
Until the date to be fixed pursuant to Article 1 (c), the units listed in Chapter 3 may be combined with 
each other or with those in Chapter 1 to form compound units. 
17.7.91 Official Journal of the European Communities No C 185/21 
CHAPTER 4 
LEGAL UNITS OF MEASUREMENT REFERRED TO IN ARTICLE I (d), PERMITTED IN 
SPECIALIZED FIELDS ONLY 
Field of application 
Marine navigation 
Beer, cider, waters, lemonades 
and fruit juices in returnable 
containers 
Spirit drinks 
Goods sold loose in bulk 
Gas supply Unit 
Name 
fathom 
pint 
fluid ounce 
gill 
ounce 
(avoirdupois) 
pound 
therm Approximate value 
1 fm = 1,829 m 
1 pt = 0,5683 x 10-W 
1 fl oz - 28,41 x lO-'m5 
1 gill = 0,142 x 10-W 
1 oz = 28,35 x 10-J kg 
1 lb = 0,4536 kg 
1 therm = 105,506 x 10*J Symbol 
fm 
Pt 
fl oz 
gill 
oz 
lb 
therm 
Until the date to be fixed pursuant to Article 1 (d), the units listed in this Chapter may be combined with 
each other or with those in Chapter 1 to form compound units. 
ANNEX II 
Directive 
80/181/EEC (OJ No L 39, 15. 2. 1980, p. 40) 
85/1/EEC (OJ No L 2, 3. 1. 1985, p. 11) 
89/617/EEC (OJ No L 357, 7. 12. 1989, p. 28) Deadline for implementation 
1 July 1981 
1 July 1985 
30 November 1991