SI, or Système international, units are an internationally standardized set of metric units built up from base units, prefixes and derived units. With Wolfram|Alpha, you can perform unit conversions using the base SI units, consisting of the meter for length, kilogram for mass, second for time, ampere for electric current, kelvin for temperature, mole for an amount of a substance and candela for luminous intensity, or derived SI units, such as the joule for energy, volt for electric potential difference and many others. You can also do calculations using compound units, such as meters per second for speed and kilograms per cubic meter for mass density, or explore the names and values of the set of prefixes defined in the SI system.
Convert between SI and other units and obtain additional information about them.
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Explore SI prefix names and values.