# What are the seven fundamental units?

Jun 2, 2018

The SI units for the seven fundamental measurable qualities are:

• $\text{A}$, ampere, a unit of electrical current
• $\text{cd}$, candela, a unit of luminous intensity
• $\text{K}$, kelvin, a unit of absolute temperature
• $\text{kg}$, kilogram, a unit of mass
• $\text{m}$, meter, a unit of distance
• $\text{mol}$, mole, a unit of quantity/counting
• $\text{s}$, second, a unit of time

Of course, we also have prefixes that can be appended to all of these as we wish, to express them in nicer numerical magnitudes, e.g.

• $\text{pm}$, picometers, for atomic radii
• $\text{ns}$, nanoseconds, for some first-order mean lifetime $\tau \equiv {k}^{- 1}$ of a fluorescent molecule
• $\text{mg}$, milligrams, for typical solid/powder drug prescriptions
• $\text{mm}$, millimeters, for measurements using a caliper