Arrhenius Calculator
Calculator
\[ k = A \cdot e^{-E_a / RT} \]
k = rate constant, A = pre-exponential (frequency) factor, Ea = activation energy (J/mol), R = 8.314 J·mol⁻¹·K⁻¹, T = temperature (K).
Arrhenius Equation
Result
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Two-Temperature Rate Comparison
\[ \ln\frac{k_2}{k_1} = \frac{E_a}{R}\left(\frac{1}{T_1} - \frac{1}{T_2}\right) \]

Given Ea and two temperatures, find k₂/k₁. Or given k₁, k₂, T₁, T₂ — find Ea.

About This Tool

The Arrhenius equation, k = A·e−Ea/RT, describes how the rate constant of a chemical reaction depends on temperature and activation energy. This calculator lets you solve for any one of the three unknowns: the rate constant k, the pre-exponential (frequency) factor A, or the activation energy Ea, given the other two and a temperature. The two-temperature comparison tool uses the linearised form of the Arrhenius equation to find the ratio of rate constants at two different temperatures, or to back-calculate activation energy from experimentally measured rate constants. Common applications include reaction kinetics in physical chemistry, enzyme activity modelling in biochemistry, and shelf-life prediction in pharmaceutical and food science.