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Système International d'Unités*
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- 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 | = 1012 | |
tera |
T | |
0.1 | = 101 | |
deci |
d |
1 000 000 000 | = 109 | |
giga |
G | |
0.01 | = 102 | |
centi |
c |
1 000 000 | = 106 | |
mega |
M | |
0.001 | = 103 | |
milli |
m |
1 000 | = 103 | |
kilo |
k | |
0.000 001 | = 106 | |
micro |
µ |
100 | = 102 | |
hecto |
h | |
0.000 000 001 | = 109 | |
nano |
n |
10 | = 101 | |
deca |
da | |
0.000 000 000 001 | = 1012 | |
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 |
m2 |
|
volume |
cubic metre |
m3 |
|
frequency |
hertz |
Hz |
1/s |
mass density (density) |
kilogram per cubic metre |
kg/m3 |
|
speed, velocity |
metre per second |
m/s |
|
angular velocity |
radian per second |
rad/s |
|
acceleration |
metre per second squared |
m/s2 |
|
angular acceleration |
radian per second squared |
rad/s2 |
|
force |
newton |
N |
kg · m/s2 |
pressure (mechanical stress) |
newton per square metre |
N/m2 |
|
kinematic viscosity |
square metre per second |
m2/s |
|
dynamic viscosity |
newton-second per square metre |
N · s/m2 |
|
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/m2 |
magnetic field strength |
ampere per metre |
A/m |
|
magnetomotive force |
ampere |
A |
|
luminous flux |
lumen |
lm |
cd · sr |
luminance |
candela per square metre |
cd/m2 |
|
illuminance |
lux |
lx |
lm/m2 |
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Reference: |
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Comptes Rendus de la 11e CGPM (1960), 1961, p.87
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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).
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The reader should note that the official version of this Resolution is the French text.
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