☙

Planck mass

A unit of mass in an absolute system of units devised by Max Planck, about 2.176 434 × 10⁻⁵ gram¹. Symbol, m_P. Algebraically, it is

$the square root of a fraction. h-bar c is the numerator. G is the denominator.$

where c = the speed of light, G = Newtonian gravitational constant, and ħ = the reduced Planck's constant.

1. This is the 2018 CODATA value. For the most up-to-date value, see NIST's CODATA pages: https://www.physics.nist.gov/cgi-bin/cuu/Value?plkm this link goes to a new page