Arrhenius Equation Calculator

Rate constants, and where the 'doubles per 10 degrees' rule comes from.

Rate constants, and where the 'doubles per 10 degrees' rule comes from. k = A·e^(−Ea/RT).

Written and maintained by Mohit PatelLast checked August 4, 2026How we build these

Pre-exponential factor (A)

Activation energy (Ea)

kJ/mol

Temperature

°C

Rate constant k

17,393.1797

1.924× faster per 10 K

Rate constant k17,393.17969

Activation energy50 kJ/mol

Speed-up per 10 K1.9243×

Temperature298.15 K

k = A·e^(−Ea/RT). The exponential is why the old laboratory rule of thumb — that reaction rate roughly doubles for every 10 °C — holds at all: it is not a law, it is what this equation produces for activation energies around 50 kJ/mol near room temperature. Change Ea and the factor changes with it, which the row above makes visible.

How the Arrhenius Equation Calculator works

k = A·e^(−Ea/RT). The old laboratory rule that reaction rate roughly doubles every 10 °C is not a law. It is what this equation produces for activation energies around 50 kJ/mol near room temperature. Change Ea and the factor changes with it.

Also known as: activation energy calculator · rate constant calculator · arrhenius formula · how to calculate activation energy

Where to go next

The Arrhenius Equation question rarely arrives on its own. These are the ones that usually come with it:

Gibbs Free Energy Calculator — ΔG = ΔH − TΔS, with the unit mismatch handled.
Equilibrium Constant Calculator — Kp from Kc, with Δn counting gases only.
Half-Life Calculator — Exponential decay, and why it never reaches zero.
Speed Distance Time Calculator — Any one of the three from the other two, in four units.

Sources

Frequently asked questions

What is the Arrhenius equation?

k = A·e^(−Ea/RT), relating the rate constant to activation energy and absolute temperature.

Does reaction rate really double every 10 degrees?

Only approximately, and only for typical activation energies near room temperature. This page shows the actual factor for your figures rather than repeating the rule of thumb.

What is the pre-exponential factor?

Roughly, how often correctly-oriented collisions occur. It sets the ceiling the exponential term scales down from.

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