Advanced Electrochemical Cell Voltage Calculator

Enter electrochemical cell inputs

Use reduction potentials for both half-cells. Enter activity or concentration as 1 for pure solids and pure liquids.

Cathode standard reduction potential, E°cathode (V)

Example: Cu²⁺/Cu = 0.34 V.

Anode standard reduction potential, E°anode (V)

Example: Zn²⁺/Zn = -0.76 V.

Electrons transferred, n

Use the balanced overall reaction value.

Temperature (K)

298.15 K is standard laboratory temperature.

Reaction quotient mode

Choose automatic or direct Nernst input.

Manual reaction quotient, Q

Used only when manual mode is selected.

Cathode oxidized-form activity

Reactant at the cathode half-reaction.

Cathode reduced-form activity

Product at the cathode half-reaction.

Anode oxidized-form activity

Product at the anode oxidation side.

Anode reduced-form activity

Reactant consumed at the anode side.

Cathode oxidized-form coefficient

Exponent used in the denominator of Q.

Cathode reduced-form coefficient

Exponent used in the numerator of Q.

Anode oxidized-form coefficient

Exponent used in the numerator of Q.

Anode reduced-form coefficient

Exponent used in the denominator of Q.

Formula used

E°cell = E°cathode − E°anode

Ecell = E°cell − (RT / nF) ln(Q)

Ecell = E°cell − (2.303RT / nF) log10(Q)

ΔG = −nFEcell

K = 10^[(nFE°cell) / (2.303RT)]

E°cell = standard cell voltage in volts.
Ecell = actual cell voltage at the entered conditions.
R = gas constant, 8.314462618 J/mol·K.
T = temperature in kelvin.
n = electrons transferred in the balanced reaction.
F = Faraday constant, 96485.33212 C/mol.
Q = reaction quotient. For the generic combined reaction shown by your half-cells, Q = (a_{cathode,reduced}^ν × a_{anode,oxidized}^ν) / (a_{cathode,oxidized}^ν × a_{anode,reduced}^ν).

How to use this calculator

Enter the cathode and anode standard reduction potentials.
Provide the total electrons transferred in the balanced overall reaction.
Enter the system temperature in kelvin.
Choose whether to calculate Q automatically or enter it manually.
If you use automatic mode, enter activities or concentrations for the four species and their stoichiometric exponents.
Use a value of 1 for pure solids and pure liquids because their activity is commonly taken as unity.
Press Calculate Cell Voltage to display the result block above the form.
Download the summary as CSV or PDF when you need lab, academic, or reporting records.

Example data table

Example cell	E°cathode (V)	E°anode (V)	n	T (K)	Q	E°cell (V)	Ecell (V)
Zn \| Zn²⁺ \|\| Cu²⁺ \| Cu	0.34	-0.76	2	298.15	0.20	1.10	1.1207
Fe \| Fe²⁺ \|\| Ag⁺ \| Ag	0.80	-0.44	2	298.15	0.50	1.24	1.2489
Cd \| Cd²⁺ \|\| Cu²⁺ \| Cu	0.34	-0.40	2	310.15	2.00	0.74	0.7307

Frequently asked questions

1) What does the standard cell voltage mean?

E°cell is the voltage difference under standard-state conditions. It comes from subtracting the anode reduction potential from the cathode reduction potential.

2) When should I use the Nernst equation?

Use it whenever concentrations, activities, or pressures differ from standard conditions. It adjusts the standard voltage to match the actual chemical environment.

3) Why can solids be entered as 1?

Pure solids and pure liquids usually have unit activity in electrochemical calculations. Setting them to 1 keeps the quotient focused on dissolved or gaseous species.

4) What does a positive calculated voltage indicate?

A positive Ecell means the reaction is spontaneous as written under the entered conditions. Negative voltage means the reverse direction is favored.

5) Why does concentration change voltage?

Changing species activity alters the reaction quotient Q. The Nernst term responds to Q, so the cell potential rises or falls accordingly.

6) What is the reaction quotient Q?

Q compares product activities to reactant activities, each raised to their stoichiometric powers. It measures how far the reaction has moved from standard conditions.

7) Can I use activities instead of concentrations?

Yes. Activities are preferred for rigorous work because they account for nonideal behavior. Concentrations are a practical approximation in many educational or dilute systems.

8) Why might real measurements differ from this result?

Measured values can shift because of liquid junction potentials, electrode polarization, resistance losses, temperature drift, impurities, or inaccurate activity estimates.