In physics and chemistry, the Faraday constant is the amount of electric charge of one mole of electrons.

It has the symbol F, and is given by

,

where N_A is Avogadro's number (approximately 6.02 x 10²³) and q is the charge on an electron.

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. This value was used to calculate Avogadro's number. Research is continuing into more accurate ways of determining F, and thereby N_A. There are plans to use this value to redefine the kilogram in terms of a known number of atoms. [Source: NPL Annual Review 1999]

F = 96 485.309 29 C/mol ± 0.028 945 6 C/mol [Horner's Physics Constants, 1999]

F = 96 485.3415 C/mol ± 0.0039 C/mol [NIST, 2003, quoting CODATA, 1998]

The Faraday constant was named after British scientist Michael Faraday.