Electrochemical Cell EMF Calculator

Summary

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

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