système international d'unités
Notes on SI, the world’s most used system of measurement.
base
There are seven base units.
| unit | symbol | measures |
|---|---|---|
| ampere | A | electric current |
| candela | cd | luminous intensity |
| kelvin | K | thermodynamic temperature |
| kilogram | kg | mass |
| metre | m | length |
| mole | mol | amount of substance |
| second | s | time |
prefixes
There are 24 prefixes.
| prefix | symbol | base 10 | decimal |
|---|---|---|---|
| quetta | Q | 1030 | |
| ronna | R | 1027 | |
| yotta | Y | 1024 | |
| zetta | Z | 1021 | |
| exa | E | 1018 | |
| peta | P | 1015 | |
| tera | T | 1012 | |
| giga | G | 109 | |
| mega | M | 106 | |
| kilo | k | 103 | |
| hecto | h | 102 | 100 |
| deca | da | 101 | 10 |
| — | — | 100 | 1 |
| deci | d | 10-1 | |
| centi | c | 10-2 | |
| milli | m | 10-3 | |
| micro | μ | 10-6 | 0.000 001 |
| nano | n | 10-9 | 0.000 000 001 |
| pico | p | 10-12 | 0.000 000 000 001 |
| femto | f | 10-15 | 0.000 000 000 000 001 |
| atto | a | 10-18 | 0.000 000 000 000 000 001 |
| zepto | z | 10-21 | 0.000 000 000 000 000 000 001 |
| yocto | y | 10-24 | 0.000 000 000 000 000 000 000 001 |
| ronto | r | 10-27 | 0.000 000 000 000 000 000 000 000 001 |
| quecto | q | 10-30 | 0.000 000 000 000 000 000 000 000 000 001 |