Mass of electron: Learn about the electron mass

Learn about the electron mass , a fundamental constant of physics that has a value of about 9.109 × 10−31 kg or 5.486 × 10−4 Da. Find out how it is measured, calculated and related to other physical constants. The mass of electron is the mass of a stationary electron described by the equation me = 9.10938356 × 10-31 kilograms where me is the rest mass of electron . Therefore, electrically neutral atoms/molecules must have an equal number of electrons and protons. Although the magnitude of the charges held by protons and electrons are the same, the size and mass of an electron are much smaller than that of a proton (the mass of an electron is roughly 1/1837 the mass of a proton).