# Natural units

From Conservapedia

**Natural units** are units of measurement that arise when a physical constant, such as Planck's constant or the speed of light in a vacuum, is set to a dimensionless value such as one.^{[1]} For example, in natural units, since *c* is set to unity, mass and energy can be expressed in the same units. Therefore, the masses of subatomic particles are often expressed in in electron volts, which are a unit of energy.

Radians used in geometry are one example of a natural constant, since they are defined so that pi radians make a half-turn (more widely known as 180 degrees).