

Système International d'Unités


The 11th Conférence Générale des Poids et Mesures (CGPM),
considering
Resolution 6 of the 10th CGPM, by which it adopted six base units on which to establish a practical system of measurement for international use:
length 
metre 
m 
mass 
kilogram 
kg 
time 
second 
s 
electric current 
ampere 
A 
thermodynamic temperature 
degree Kelvin 
°K 
luminous intensity 
candela 
cd 
Resolution 3 adopted by the Comité International des Poids et Mesures (CIPM) in 1956,
the recommendation adopted by the CIPM in 1958 concerning an abbreviation for the name of the system, and prefixes to form multiples and submultiples of the units,
decides
 the system founded on the six base units above is called the "Système International d'Unités";
 the international abbreviation of the name of the system is SI;
 names of multiples and submultiples of the units are formed by means of the following prefixes:
Multiplying factor 
 Prefix 
Symbol  
Multiplying factor 
 Prefix 
Symbol 

1 000 000 000 000  = 10^{12}  
tera 
T  
0.1  = 10^{–1}  
deci 
d 
1 000 000 000  = 10^{9 }  
giga 
G  
0.01  = 10^{–2}  
centi 
c 
1 000 000  = 10^{6 }  
mega 
M  
0.001  = 10^{–3}  
milli 
m 
1 000  = 10^{3 }  
kilo 
k  
0.000 001  = 10^{–6}  
micro 
µ 
100  = 10^{2 }  
hecto 
h  
0.000 000 001  = 10^{–9}  
nano 
n 
10  = 10^{1 }  
deca 
da  
0.000 000 000 001  = 10^{–12}  
pico 
p 
 the units listed below are used in the system, without excluding others which might be added later.
Supplementary units
plane angle 
radian 
rad 
solid angle 
steradian 
sr 
Derived units
area 
square metre 
m^{2} 

volume 
cubic metre 
m^{3} 

frequency 
hertz 
Hz 
1/s 
mass density (density) 
kilogram per cubic metre 
kg/m^{3} 

speed, velocity 
metre per second 
m/s 

angular velocity 
radian per second 
rad/s 

acceleration 
metre per second squared 
m/s^{2} 

angular acceleration 
radian per second squared 
rad/s^{2} 

force 
newton 
N 
kg · m/s^{2} 
pressure (mechanical stress) 
newton per square metre 
N/m^{2} 

kinematic viscosity 
square metre per second 
m^{2}/s 

dynamic viscosity 
newtonsecond per square metre 
N · s/m^{2} 

work, energy, quantity of heat 
joule 
J 
N · m 
power 
watt 
W 
J/s 
quantity of electricity 
coulomb 
C 
A · s 
tension (voltage), potential difference, electromotive force 
volt 
V 
W/A 
electric field strength 
volt per metre 
V/m 

electric resistance 
ohm 

V/A 
capacitance 
farad 
F 
A · s/V 
magnetic flux 
weber 
Wb 
V · s 
inductance 
henry 
H 
V · s/A 
magnetic flux density 
tesla 
T 
Wb/m^{2} 
magnetic field strength 
ampere per metre 
A/m 

magnetomotive force 
ampere 
A 

luminous flux 
lumen 
lm 
cd · sr 
luminance 
candela per square metre 
cd/m^{2} 

illuminance 
lux 
lx 
lm/m^{2} 






Reference: 


Comptes rendus de la 11^{e} CGPM (1960), 1961, 87



Note:
The CGPM later abrogated certain of its decisions and extended the list of prefixes:
 The name and symbol for the unit of thermodynamic temperature were modified by the 13th CGPM in 1967 (Resolution 3).
 A seventh base unit, the mole, was adopted by the 14th CGPM in 1971 (Resolution 3).
 Further prefixes were adopted by the 12th CGPM in 1964 (Resolution 8), the 15th CGPM in 1975 (Resolution 10), and the 19th CGPM in 1991 (Resolution 4).
 The 20th CGPM in 1995 abrogated the class of supplementary units in the SI (Resolution 8). These are now considered as derived units.
 The 13th CGPM in 1967 (Resolution 6) specified other units which should be added to this list of derived units. In principle, the list is without limit.
 Modern practice is to use the phrase "amount of heat" rather than "quantity of heat", because the word quantity has a different meaning in metrology.
 Modern practice is to use the phrase "amount of electricity" ranther than "quantity of electrcity" (see above).






