Nernst Equation Calculator – Free, with Steps

Nernst equation calculator: cell potential under non-standard conditions from E°, temperature, electrons transferred and Q.

How to use this calculator

Choose the quantity you want under “Solve for”.
Type the known values and pick their units: any combination works.
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The Nernst equation gives the potential of an electrochemical cell away from standard conditions: E = E° − (RT/zF)·ln Q, where Q is the reaction quotient and z the electrons transferred.

At 25 °C, RT/F = 25.69 mV, so the familiar form is E = E° − (0.05916 V/z)·log₁₀Q. When the cell reaches equilibrium, E = 0 and Q = K.

Formula

E = E° − R · Tz · F · ln Q

Symbol	Quantity	Units
E°	Standard cell potential	V, mV, µV, kV
T	Temperature	K, °C, °F, °R
z	Electrons transferred	—
Q	Reaction quotient	—
E	Cell potential	V, mV, µV, kV

Constants used: R = 8.314462618 J·mol⁻¹·K⁻¹ · F = 96,485.33212 C·mol⁻¹

Worked example

Given: E° = 1.1 V · T = 25 °C · z = 2 · Q = 0.01

E = E° − R·Tz·F ln Q

Result: E = 1.15916 V

Cell potential for different values of Standard cell potential

E° · Standard cell potential	E · Cell potential
0.55 V	0.60916 V
0.825 V	0.88416 V
0.99 V	1.0492 V
1.1 V	1.1592 V
1.21 V	1.2692 V
1.375 V	1.4342 V
1.65 V	1.7092 V
2.2 V	2.2592 V

Other values as in the worked example.

Frequently asked questions

How do I get the equilibrium constant from E°?

Set E = 0 and solve for Q: K = e^(zFE°/RT).

What is Q for a Daniell cell?

For Zn + Cu²⁺ → Zn²⁺ + Cu, Q = [Zn²⁺]/[Cu²⁺]. Pure solids are left out.

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Last updated: November 7, 2026 · Report an error