The Planck mass is the fundamental unit of mass in the system of Planck units. It has the value:

*m*kg_{P}= 2.18 × 10^{8}In SI units, measurements of mass are made in kilograms (usually given the symbol

**kg**). While the kilogram is convenient for use in everyday life, such as measuring the mass of a person or the mass of ingredients for a cake, it becomes less practical when we discuss the masses of the elementary particles such as the proton (rest mass of 1.67 × 10^{-27}kg) and the electron (rest mass about 1/1800 that of the proton).A consequence of using kilograms to measure mass is that the fundamental constants take on values that are not always convenient for including in equations:

Speed of light *c*= 299792458 m s^{-1}Gravitational constant *G*= 6.673(10) x 10^{-11}m^{3}kg^{-1}s^{-2}Plank's constant (reduced) = *h*/2π = 1.054571596(82) x 10^{-34}kg m^{2}s^{-1}Boltzmann constant *k*= 1.3806502(24) x 10^{-23}kg m^{2}s^{-2}K^{-1}The Planck mass is derived dimensionally using combinations of these fundamental constants:

By redefining the base units for length, mass and time in terms of the Planck units, the fundamental constants have the values:

*c*=*G*= =*k*= 1.