Electrochemical Cell EMF Calculator

Enter the standard reduction potentials for the cathode and anode half-cells to instantly calculate the standard EMF of the electrochemical cell.

Use the Electrochemical Cell EMF Calculator

Cell Inputs

E°cell = E°cathode − E°anode

V

Reduction occurs here — higher reduction potential half-cell.

V

Oxidation occurs here — enter as standard reduction potential.

mol e⁻

Number of moles of electrons in the balanced overall reaction.

Common Cells (click to fill)

Enter half-cell potentials on the left and click Calculate EMF.

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Summary

The Electrochemical Cell EMF Calculator computes the standard electromotive force (E°cell) of a galvanic or electrolytic cell using the relation E°cell = E°cathode − E°anode, where both half-cell potentials come from standard reduction potential tables measured at 25 °C and 1 M concentration. It also predicts spontaneity via the sign of E°cell and calculates the standard Gibbs free energy change (ΔG° = −nFE°cell). All calculations run entirely in your browser with no data sent to any server.

How it works

  1. Look up the standard reduction potential (E°) for each half-reaction from a standard electrochemistry table.
  2. Enter the cathode (reduction) half-cell potential — this is the half-cell with the higher reduction potential.
  3. Enter the anode (oxidation) half-cell potential — this is the half-cell where oxidation occurs.
  4. Enter the number of electrons (n) transferred in the balanced overall reaction.
  5. Click Calculate; the tool applies E°cell = E°cathode − E°anode and shows EMF, spontaneity, and ΔG°.
  6. Review the breakdown showing each step, the spontaneity verdict, and the standard Gibbs free energy.

Use cases

  • Determine the voltage of a standard galvanic cell such as the Daniell cell (Zn/Cu).
  • Predict whether a redox reaction is spontaneous under standard conditions.
  • Calculate standard Gibbs free energy change (ΔG°) from cell potential.
  • Solve electrochemistry homework problems and check hand calculations.
  • Compare multiple electrode combinations to find the highest-voltage cell design.
  • Understand which half-cell acts as cathode and which acts as anode.
  • Prepare for AP Chemistry, university general chemistry, or physical chemistry exams.
  • Verify textbook answers for standard cell potential problems.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu