SI
Updated: 12/31/2022 by Computer Hope
SI may refer to any of the following:
1. Alternatively called the metric system, SI or SI units is an internationally accepted set of seven base units of measurements (time, length, mass, electric current, thermodynamic temperature, amount of substance, luminous intensity), named derived units, and 24 prefixes. SI is abbreviated from the French "Le Système International d'Unités." Today, the United States is the only country not completely committed to the metric system.
SI named derived units
- becquerel
- Celsius
- coulomb
- farad
- gray
- henry
- hertz
- katal
- joule
- lumen
- lux
- newton
- ohm
- pascal
- radian
- siemens
- sievert
- steradian
- tesla
- volt
- watt
- weber
SI prefixes
| Prefix | Symbol | Base 10 | Decimal | Scale |
|---|---|---|---|---|
| quetta- | Q | 1030 | 1,000,000,000,000,000,000,000,000,000,000 | nonillion |
| ronna- | R | 1027 | 1,000,000,000,000,000,000,000,000,000 | octillion |
| yotta- | Y | 1024 | 1,000,000,000,000,000,000,000,000 | septillion |
| zetta- | Z | 1021 | 1,000,000,000,000,000,000,000 | sextillion |
| exa- | E | 1018 | 1,000,000,000,000,000,000 | quintillion |
| peta- | P | 1015 | 1,000,000,000,000,000 | quadrillion |
| tera- | T | 1012 | 1,000,000,000,000 | trillion |
| giga- | G | 109 | 1,000,000,000 | billion |
| mega- | M | 106 | 1,000,000 | million |
| kilo- | k | 103 | 1,000 | thousand |
| hecto- | h | 102 | 100 | hundred |
| deca- | da | 101 | 10 | ten |
| 100 | 1 | one | ||
| deci- | d | 10-1 | 0.1 | tenth |
| centi- | c | 10-2 | 0.01 | hundredth |
| milli- | m | 10-3 | 0.001 | thousandth |
| micro- | µ | 10-6 | 0.000,001 | millionth |
| nano- | n | 10-9 | 0.000,000,001 | billionth |
| pico- | p | 10-12 | 0.000,000,000,001 | trillionth |
| femto- | f | 10-15 | 0.000,000,000,000,001 | quadrillionth |
| atto- | a | 10-18 | 0.000,000,000,000,000,001 | quintillionth |
| zepto- | z | 10-21 | 0.000,000,000,000,000,000,001 | sextillionth |
| yocto- | y | 10-24 | 0.000,000,000,000,000,000,000,001 | septillionth |
| ronto- | r | 10-27 | 0.000,000,000,000,000,000,000,000,001 | octillionth |
| quecto- | q | 10-30 | 0.000,000,000,000,000,000,000,000,000,001 | nonillionth |
2. Si is also the abbreviation for silicon.
3. The top-level domain .si is short for Slovenia.