What This Calculator Does
This tool calculates a chemical reaction’s rate constant (k) using the Arrhenius equation, which links how fast a reaction proceeds to its activation energy and the temperature it runs at.
The Formula
The Arrhenius equation is k = A × e-Ea/(RT), where A is the pre-exponential (frequency) factor, Ea is the activation energy in joules per mole, R is the universal gas constant (8.314 J/(mol·K)), and T is the absolute temperature in kelvin. Because k can span many orders of magnitude, the result is also shown as a mantissa and power-of-ten exponent (k = m × 10^n) so very small or very large values stay readable.
A Few Notes
- Temperature must be converted to kelvin before use in the equation; this calculator does that conversion for you if you enter Celsius.
- The units of k depend on the reaction order (matching the units of A you enter) — this calculator doesn’t assume a specific order.
- Intended for general chemistry education and reaction-kinetics estimation, not as a substitute for experimentally measured rate data.
Last reviewed August 2026