Nernst Equation Calculator
Compute the actual electrochemical cell potential under non-standard concentrations using the Nernst equation.
V
K
Non-standard EMF from the Nernst equation
- 1
Thermal slope R·T ÷ (n·F)
8.314 × 298 ÷ (2 × 96485) = 0.01284Volts per natural-log unit of Q. - 2
Natural log of Q
ln(0.001) = -6.9078 - 3
Nernst correction
slope × ln(Q) = 0.01284 × -6.9078 = -0.0887 - 4
Cell potential E
E° − correction = 1.1 − (-0.0887) = 1.1887
How does this calculator work?
The Nernst equation gives a cell’s actual potential under non-standard conditions: E = E° − (R·T/nF)·ln(Q). At 298 K it simplifies to E = E° − (0.05916/n)·log₁₀(Q). Enter the standard potential, electrons transferred, reaction quotient, and temperature to get E and see how it varies with log₁₀(Q).
Formula
How this is calculated
The standard cell potential E° (in volts) is the EMF when every species is at unit activity. The number of electrons n is the moles of electrons exchanged in the balanced redox reaction, and the reaction quotient Q is the activity ratio of products to reactants at the moment of interest. The optional temperature T (kelvin) defaults to 298 K (25 °C).
The Nernst equation corrects E° for non-standard conditions: E = E° − (R·T / (n·F))·ln(Q), where R = 8.314 J·mol⁻¹·K⁻¹ is the gas constant and F = 96485 C·mol⁻¹ is the Faraday constant. The term R·T/(n·F) is the thermal voltage scaled by n. Converting the natural log to base-10 (ln Q = 2.303·log₁₀Q) gives the familiar 25 °C form E = E° − (0.05916/n)·log₁₀(Q), where 0.05916 V is 2.303·R·T/F at 298 K.
Q must be strictly positive because the logarithm is undefined for Q ≤ 0, and n must be non-zero. When Q = 1 the log term vanishes and E equals E°. As products accumulate Q rises, log₁₀Q grows and E falls toward zero; the cell reaches equilibrium (E = 0) when log₁₀Q = n·E°/0.05916. The plot shows E as a linear function of log₁₀Q with slope −0.05916/n volts per decade (scaled by T/298 at other temperatures).
Frequently asked questions
The factor 2.303·R·T/F equals 0.05916 V at T = 298 K. Dividing by n gives the change in potential per ten-fold change in Q. At other temperatures the slope scales linearly with T.
Q is the ratio of product activities to reactant activities, each raised to its stoichiometric coefficient, evaluated at the current (non-equilibrium) conditions. At equilibrium Q equals K and the cell potential E is zero.
Yes. Enter the standard electrode potential as E°, the electrons in that half-reaction as n, and the appropriate Q for the half-reaction to get the non-standard electrode potential.
Also known as
TG we-Calculate Editorial Team. (2026). Nernst Equation Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/nernst-equation-calculator
TG we-Calculate Editorial Team. "Nernst Equation Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/nernst-equation-calculator.
TG we-Calculate Editorial Team, "Nernst Equation Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/nernst-equation-calculator
@misc{wecalculate_nernst_equation_calculator, title = {Nernst Equation Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/nernst-equation-calculator}}, year = {2026}, note = {TG we-Calculate} }
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