What is activation energy?
Activation energy (Ea) is the minimum energy that reacting molecules need to successfully collide and form products. It is a key parameter in the Arrhenius equation and determines how sensitive a reaction rate is to temperature changes.
How this calculator works
Given two rate constants measured at two different temperatures, this calculator uses the two-point form of the Arrhenius equation, derived by taking the natural log of k = A·e^(-Ea/RT) at both temperatures and subtracting: Ea = R · ln(k2/k1) / (1/T1 – 1/T2), where R = 8.314 J/(mol·K).
Note: Both rate constants must come from the same reaction under otherwise identical conditions, with temperatures entered in kelvin. This tool is intended for general chemistry education and planning purposes.
Last reviewed August 2026