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The International System of units SI consists of a set of base units, derived units and prefixes. This article series provides basic information about the SI units and how they are realised in Finland.
The seven base units of the seven base quantities in the SI are:
| SI base unit | ||
| Base quantity | Name | Symbol |
| length | metre | m |
| mass | kilogram | kg |
| time | second | s |
| electric current | ampere | A |
| temperature | kelvin | K |
| amount of substance | mole | mol |
| luminous intensity | candela | cd |
The derived units can be formed by combining the base units according to the algebraic relations linking the corresponding quantities, for instance the SI coherent derived unit for density (mass density) is kg/m3. For some of the derived units a special name and special symbol is given, for instance, the derived unit for force is Newton, N (kg·m·s–2).
The SI prefixes are used to form decimal multiples and submultiples of SI units:
| Factor | Name | Symbol | Factor | Name | Symbol |
| 101 | deca | da | 10–1 | deci | d |
| 102 | hecto | h | 10–2 | centi | c |
| 103 | kilo | k | 10–3 | milli | m |
| 106 | mega | M | 10–6 | micro | µ |
| 109 | giga | G | 10–9 | nano | n |
| 1012 | tera | T | 10–12 | pico | p |
| 1015 | peta | P | 10–15 | femto | f |
| 1018 | exa | E | 10–18 | atto | a |
| 1021 | zetta | Z | 10–21 | zepto | z |
| 1024 | yotta | Y | 10–24 | yokto | y |
More information on
- the International System of Units (SI): https://www.bipm.org/en/measurement-units/
- the future revision of the SI: https://www.bipm.org/en/measurement-units/rev-si/
Article series about SI units
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