Electrochemical cell & Nernst equation calculator

How to use (3 steps)

Choose a mode: standard cell, Nernst equation, or concentration cell.
Enter standard potentials, electron count n, temperature (K), and concentrations or Q as needed.
Compute to see E°, ΔG°, K, E under non-standard conditions, and the calculation log. Copy the URL to share.

A default Zn|Zn²⁺ || Cu²⁺|Cu example is prefilled. Press Compute to generate cell voltage, ΔG°, K, and the calculation log.

Inputs

Pick a mode, adjust the example values, then compute or copy the URL. Units use volts and mol/L for clarity.

Standard cell (E°, ΔG°, K) Nernst equation Concentration cell

Anode half-reaction (label)

Anode E° (V)

Cathode half-reaction (label)

Cathode E° (V)

Electrons n

The standard cell mode assumes standard conditions at 25 °C (about 298 K). For other temperatures or non-standard concentrations, use the Nernst equation or concentration cell modes.

Enter the more concentrated half-cell in the first box and the more dilute half-cell in the second. Swapping them flips the sign of E.

Results

Mode: Standard cell (E°, ΔG°, K)

How it's calculated

Run the calculation to list the Nernst substitutions and checks.

Use this page after the redox reaction is already balanced

This calculator is for turning a known balanced cell reaction into E, ΔG, K, or Nernst-equation outputs. Open Chemical Equilibrium ICE Table for equilibrium concentration work, use Chemical Equation Balancer before you choose n, and switch to Stoichiometry & Limiting Reactant when yield or reagent ratios are the actual question.

Confirm the overall balanced reaction and electron count before entering values.
Choose standard, Nernst, or concentration-cell mode based on the physical setup.
Keep temperature and quotient assumptions aligned when comparing runs.

FAQ

Do I need to balance the overall redox equation?

This tool assumes you have already combined and balanced the half-reactions, so the electron count n you enter matches the balanced overall cell reaction. It does not balance redox equations for you, but it does show how E°, ΔG°, K and the Nernst equation relate once n is known.

When should I use the concentration cell mode instead of the general Nernst mode?

Use the concentration cell mode when both half-cells are the same metal/ion pair and only the ion concentration differs. For more complicated cells (different half-reactions on each side), use the general Nernst mode and compute Q from the balanced reaction stoichiometry.

Which Nernst mode should I choose?

Use standard cell mode when all species are at standard conditions, Nernst mode when you know the reaction quotient Q, and concentration cell mode when the same redox pair appears on both sides with different ion concentrations.

How should I define the reaction quotient Q?

Build Q from the balanced overall cell reaction using product activities over reactant activities, each raised to its stoichiometric coefficient. Leave pure solids and liquids out of Q.

What does temperature change in the calculation?

Temperature changes the RT/nF term in the Nernst equation, so the same Q can shift the non-standard cell potential more or less strongly as T changes.

When is the standard potential E° enough?

E° is enough for standard-state comparisons and for deriving ΔG° or K. Use the Nernst equation when concentrations, pressures, or temperature differ from the standard assumptions.

Related calculators

Chemical equilibrium ICE table
Set up Kc or Kp tables and compare equilibrium shifts with the same reaction-direction logic used in the Nernst mode.
Chemical Equation Balancer + Stoichiometry
Balance the overall reaction before choosing the electron count n and building the reaction quotient Q.
Stoichiometry & limiting reactant
Translate balanced coefficients into mole ratios when the electrochemical setup is part of a larger reaction worksheet.
Beer-Lambert law & calibration curve
Use this when your electrochemistry workflow also needs concentration estimates from absorbance data.

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