Standard Cell Potential Calculator
A galvanic cell drives current because two half-reactions have different tendencies to gain electrons. The standard cell potential measures that driving force and equals the standard reduction potential of the cathode minus that of the anode. A positive value means the reaction is spontaneous under standard conditions. This calculator takes the two standard reduction potentials and the number of electrons transferred, then reports the cell potential and the standard Gibbs free energy change from delta G equals minus n times the Faraday constant times the cell potential. Look up reduction potentials from a standard electrode potential table.
Cell potential formula
E cell = E cathode - E anode (standard reduction potentials)
delta G = -n * F * E cell
F = 96,485 C/mol (Faraday constant)
E cell > 0 means spontaneous
The number of electrons n must be greater than zero. Potentials are intensive and are not scaled by coefficients. A positive cell potential gives a negative delta G.
Cell potential context
- The cathode has the higher (more positive) standard reduction potential.
- Standard reduction potentials are measured against the standard hydrogen electrode at 0 V.
- The Faraday constant is 96,485 coulombs per mole of electrons.
- A positive cell potential corresponds to a spontaneous reaction and a negative delta G.
- The Nernst equation extends this to non-standard concentrations and temperatures.
Cell potential: frequently asked questions
How do I calculate standard cell potential?
Subtract the standard reduction potential of the anode from that of the cathode: E cell = E cathode - E anode. Both values are standard reduction potentials taken from a table. A positive cell potential means the reaction is spontaneous as written.
Which electrode is the cathode?
The cathode is where reduction occurs and has the more positive (higher) standard reduction potential. The anode is where oxidation occurs and has the lower reduction potential. The cell runs so that the higher-potential half-reaction proceeds as reduction.
What does a positive cell potential mean?
A positive standard cell potential means the overall redox reaction is spontaneous under standard conditions, releasing energy. This corresponds to a negative standard Gibbs free energy change. A negative cell potential indicates a non-spontaneous reaction that requires energy input.
How is cell potential related to Gibbs free energy?
The standard Gibbs free energy change equals minus n times Faraday's constant times the cell potential: delta G = -n F E cell. Here n is the number of electrons transferred and F is the Faraday constant, 96,485 coulombs per mole. This calculator computes delta G when you enter n.
Do I need to multiply potentials by coefficients?
No. Standard reduction potentials are intensive properties and do not scale with the number of electrons or stoichiometric coefficients. You simply subtract anode from cathode. Only the Gibbs free energy and the cell current depend on the number of electrons transferred.
Official sources
- NIST CODATA: Faraday constant and fundamental constants.
- IUPAC Gold Book: standard electrode and cell potential terminology.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.