Nernst Equation Calculator
Calculate cell potential at non-standard concentrations using the Nernst equation.
About Nernst Equation Calculator
The Nernst equation corrects standard potential for actual concentrations. The 59.2 mV per decade slope at 25 °C is what makes pH electrodes work, since each pH unit shifts the potential by that amount. Nernst slope is temperature dependent, which is why pH meters require temperature compensation for accurate readings.
Formula
Nernst Equation
E = E° − (RT ÷ nF) ln Q, giving 59.2 mV per decade at 25 °C for n = 1
- Q
- Reaction quotient at the actual concentrations
- 59.2 mV
- Nernst slope per decade for a one-electron process at 25 °C
Worked example
With the default values below, Nernst Equation Calculator returns Cell Potential of 1.15916. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Standard cell potentialaccepts -5–5 V
- 1.1 V
- Electrons transferredaccepts 1–10
- 2
- Reaction quotientminimum 0
- 0.01
- Temperatureaccepts -50–200 C
- 25 C
Results
- Cell Potential
- 1.15916 V
- Nernst Correction Term
- 0.05916 V
- Slope per Decade of Concentration
- 0.02959 V
- Reaction Quotient at Equilibrium
- 15,401,729,310,692,788,000,000,000,000,000,000,000.0000
- Temperature
- 298.15 K
Step by step
- 1Values used
- 2Nernst Equation
- 3Cell Potential= 1.15916 V
- 4Nernst Correction Term= 0.05916 V
- 5Slope per Decade of Concentration= 0.02959 V
- 6Reaction Quotient at Equilibrium= 15,401,729,310,692,788,000,000,000,000,000,000,000.0000
- 7Temperature= 298.15 K
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Nernst Equation calculated?
E = E° − (RT ÷ nF) ln Q, giving 59.2 mV per decade at 25 °C for n = 1 The Nernst equation corrects standard potential for actual concentrations. The 59.2 mV per decade slope at 25 °C is what makes pH electrodes work, since each pH unit shifts the potential by that amount.
Why does Nernst Equation matter?
Nernst slope is temperature dependent, which is why pH meters require temperature compensation for accurate readings.
What values do I need to enter?
This calculator takes 4 inputs: Standard cell potential, Electrons transferred, Reaction quotient, Temperature. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.