A Digital International System of Units

This website is a prototype of what a digital version of the International System of Units (the SI) might look like. It is a project of Dr. Stuart Chalk at the University of North Florida and is not affiliated with the BIPM or CIPM that are responsible for the SI.

The SI Base Units

  • second
  • meter
  • kilogram
  • ampere
  • kelvin
  • mole
  • candela

    • The SI Prefixes

    quetta (1030)ronna (1027)yotta (1024)zetta (1021)exa (1018)peta (1015)tera (1012)giga (109)mega (106)kilo (103)hecto (102)deca (101)deci (10-1)centi (10-2)milli (10-3)micro (10-6)nano (10-9)pico (10-12)femto (10-15)atto (10-18)zepto (10-21)yocto (10-24)ronto (10-27)quecto (10-30)

    The SI Derived Units with Special Names

    radiansteradianhertznewtonpascaljoulewattcoulombvoltfaradohmsiemenswebertelsahenrydegree Celsiuslumenluxbecquerelgraysievertkatal

    The Non-SI Allowed Units

  • minute (time)
  • hour
  • day
  • astronomical unit
  • degree
  • minute (angle)
  • second (angle)
  • hectare
  • liter or litre
  • tonne
  • dalton
  • electronvolt
  • neper
  • bel
  • decibel

    • The Defining Constants

  • hyperfine transition frequency of Cs
  • speed of light in vacuum
  • Planck constant
  • elementary charge
  • Boltzmann constant
  • Avogadro constant
  • luminous efficacy