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Chemistry

Gibbs Free Energy Calculator

Calculate ΔG from enthalpy, entropy and Kelvin temperature with consistent energy units.

Explicit units and model assumptionsLocal calculations with worked examples
Chemistry workspace
Chemistry workspace

Check the units, concentration basis and assumptions before interpreting the result.

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Your chemistry result

Your result

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Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter enthalpy change δh, entropy change δs, temperature.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

The method, explained

ΔG = ΔH − TΔS. Divide entropy by 1,000 to match an enthalpy input in kJ/mol.

A WORKED EXAMPLE

Using enthalpy change δh = -40 kJ/mol, entropy change δs = -100 J/(mol·K), temperature = 298.15 K, the result is -10.185 kJ/mol. Change these example inputs to match your task; use the method above to check each step.

Understanding your result

No. Thermodynamic favorability and reaction kinetics are different. A favorable reaction can still have a large activation barrier.

What to keep in mind

Use compatible standard or nonstandard quantities at the same conditions. Temperature dependence of ΔH and ΔS is not modeled. Educational calculation only; use validated procedures for laboratory work.

Reference: OpenStax Chemistry 2e — chemical quantities and models

Common questions

Does negative free energy mean a fast reaction?

No. Thermodynamic favorability and reaction kinetics are different. A favorable reaction can still have a large activation barrier.

Are my inputs uploaded?

No. This calculation runs in your browser without an account or an external API.

Methodology maintained by ClarityKit. How these tools are built and checked.