Nernst Equation Calculator

Find the cell potential under non-standard conditions from E°, the electrons transferred, and the reaction quotient — with every step shown.

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How to use the Nernst equation

The Nernst equation adjusts a cell's standard potential for real, non-standard concentrations: E = E° − (RT/nF) ln Q. Here E° is the standard cell potential, R = 8.314 J/mol·K, T is temperature in kelvin, n is the number of electrons transferred, F = 96485 C/mol is Faraday's constant, and Q is the reaction quotient. At 25 °C (298 K) the RT/F term collapses to a constant, giving the common shortcut E = E° − (0.0592/n) log₁₀ Q. A positive E means the reaction is spontaneous as written under those conditions; at equilibrium Q equals K and E = 0.

Constants: R = 8.314 J/mol·K, F = 96485 C/mol. The 0.0592 factor is RT·ln(10)/F evaluated at 298 K, so it is only exact at 25 °C.

Related tools: Gibbs free energy calculator · all biochem tools.