Calculate a first-order rate constant from the pre-exponential factor, activation energy, and temperature.
| Rate constant k | – |
Use this calculator for kinetics homework and lab reports when you have A and Ea from a plot and need k at the bath temperature.
The calculation is k = A × exp(−Ea / RT), with R = 8.314 J/(mol·K). Enter Ea in J/mol (so 50 kJ/mol is 50000) and temperature in °C or °F; the calculator converts to kelvin. The result uses the same inverse-time unit as A.
This is the two-parameter Arrhenius form. It does not include a temperature-dependent A or a non-Arrhenius curvature.
Pre-exponential A: Pre-exponential factor A, in the same unit you want for k, for example 1e12 s⁻¹.
Ea (J/mol): Activation energy in J/mol, not kJ/mol. 75 kJ/mol is 75000.
Temperature: Reaction temperature in °C or °F.
Rate constant k: First-order rate constant in the same inverse-time unit as A, written in scientific notation.
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