Metric units
- Updated 2025-02-05 01:12 UTC
The International System of Units is abbreviated “SI” from the French “le Système international d’unités”. SI is the modern form of the metric system and is a coherent and definable measurement system devised around multiples of ten. It is the planet’s most widely used system of measurement, both for everyday commerce and for engineering, science and technology.
Base SI units
Quantity |
Unit |
Symbol |
Equivalent |
Equivalent |
|---|---|---|---|---|
Length |
metre |
m |
||
Mass |
kilogram |
kg |
||
Time |
second |
s |
||
Electric current |
ampere |
A |
C/s |
|
Absolute temperature |
kelvin |
K |
||
Amount of substance |
mole |
mol |
||
Luminous intensity |
candela |
cd |
Coherent derived SI units
Quantity |
Unit |
Symbol |
Equivalent |
Equivalent |
|---|---|---|---|---|
Plane angle |
radian |
rad |
||
Solid angle |
steradian |
sr |
||
Frequency |
hertz |
Hz |
1/s |
|
Force |
newton |
N |
kg m/s² |
|
Energy |
joule |
J |
Nm |
|
Power |
watt |
W |
J/s |
VA |
Electric Charge |
coulomb |
C |
As |
|
Voltage – potential difference |
volt |
V |
W/A |
|
Electrical capacitance |
farad |
F |
C/V |
|
Electrical resistance |
ohm |
W |
V/A |
|
Magnetic flux |
weber |
Wb |
||
Magnetic flux density |
tesla |
T |
||
Inductance |
henry |
H |
||
Luminous Flux |
lumen |
lm |
||
Illumination |
lux |
lx |
lm/m² |
|
Volume |
litre |
L |
0.001 m3 |
1 dm3 |
Temperature |
Celsius |
° C |
Kelvin-273.15 K |
Further reading
- Bureau Internationale de Poids et Mesures
https://www.bipm.org/en/home/ - MetricSystem.net
https://metricsystem.net - Wikipedia article
https://en.wikipedia.org/wiki/International_System_of_Units - Britain’s Metric Muddle
https://garfnet.org.uk/cms/2008/04/14/britains-metrication-fiasco/ - Brexiteers irrational aversion the metric system
https://garfnet.org.uk/cms/2022/08/06/brexiteers-irrational-aversion-to-the-metric-system/