Arrhenius Equation Calculator

How it is calculated

The tool evaluates k = A × e^(−Ea / (R·T)). A is the pre-exponential factor, which has the same unit as k (for a first-order reaction, 1/s). Ea is the activation energy in kJ/mol, which the tool converts to J/mol. R is the gas constant 8.314462618 J/(mol·K), and T is the temperature. You enter the temperature in °C and the tool adds 273.15 to get kelvin.

Besides k, which is shown in scientific notation with four decimals, the tool shows the exponent −Ea / (R·T). A must be greater than zero, and the temperature must be above absolute zero (−273.15 °C), otherwise there is no result. Scientific notation such as 1e10 is accepted for A.

Common mistakes

• Entering Ea in J/mol instead of kJ/mol; 75000 instead of 75 makes the exponent 1000 times larger and k effectively zero.
• Typing the temperature in kelvin although the field is in °C, which adds 273.15 a second time.
• Using the A and Ea of a different reaction order or rate expression; k only has the unit that A has, so the result must be read in that unit.
• Ea given in kcal/mol from older literature without converting (1 kcal = 4.184 kJ).
• Extrapolating far beyond the temperature range where A and Ea were fitted; the Arrhenius form is an empirical fit and can fail at extremes, for example when an enzyme denatures.