In physics and chemistry, the Faraday constant (named after Michael Faraday) is the magnitude of electric charge per mole of electrons. It has the currently accepted value

F = 96,485.3365(21) C/mol.

The constant F has a simple relation to two other physical constants:

where:

e ≈ 1.6021766×10−19 C;
NA ≈ 6.022141×1023 mol−1.

NA is the Avogadro constant (the ratio of the number of particles 'N' to the amount of substance 'n' - a unit mole), and e is the elementary charge or the magnitude of the charge of an electron. This relation is true because the amount of charge of a mole of electrons is equal to the amount of charge in one electron multiplied by the number of electrons in a mole.

The value of F was first determined by weighing the amount of silver deposited in an electrochemical reaction in which a measured current was passed for a measured time, and using Faraday's law of electrolysis. Research is continuing into more accurate ways of determining the interrelated constants F, NA, and e.