Standard Cell Potential Calculator

Work out standard cell potential instantly with clear inputs, formula shown and shareable results.

About Standard Cell Potential Calculator

A cell's standard potential is the cathode's reduction potential minus the anode's, both taken from the standard reduction table without flipping signs. Copper against zinc gives 0.34 - (-0.76) = 1.10 V. The free energy follows from dG = -nFE, so that 1.10 V two-electron cell releases about 212 kJ/mol.

Formulas

Cell potential

E(cell) = E(cathode) - E(anode)

Free energy

dG = -n x F x E(cell)

Worked example

With the default values below, Standard Cell Potential Calculator returns Standard Cell Potential of 1.1000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Cathode standard reduction potential: 0.34 V
Anode standard reduction potential: -0.76 V
Electrons transferred (n)minimum 1: 2

Results

Standard Cell Potential: 1.1000 V
Standard Free Energy Change: -212.27 kJ/mol
Spontaneity: Spontaneous as written (galvanic)
Equilibrium Constant: 1.5385 × 10³⁷

Step by step

1Values used
2Cell potential
3Free energy
4Standard Cell Potential= 1.1000 V
5Standard Free Energy Change= -212.27 kJ/mol
6Spontaneity= Spontaneous as written (galvanic)
7Equilibrium Constant= 15,384,700,000,000,000,000,000,000,000,000,000,000.0000

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why not reverse the sign of the anode value?

Because the subtraction already does it. Flipping the sign and then subtracting double-counts the reversal.

What does a negative cell potential mean?

The reaction runs the other way spontaneously. Driving it as written makes it an electrolytic cell needing at least that voltage applied.