Half-life calculator (0/1/2 order)

t½ for zeroth, first, or second order in a single reactant.

Calculator

Model / formula

Integrated rate laws — use consistent time unit for k

Reaction order in [A]

Rate constant k

Initial [A]₀ (not used for first order)

Result

t½ = 69.3147 (first order: t½ = ln 2/k)

First order: $t_{1/2} = \ln 2 / k$. Zeroth/second also need [A]₀.

Educational use only. Double-check values for labs, homework, and exams.