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EPA On-line Tools for Site Assessment Calculation

Half lives and rate constants are related through the formula t1/2 = 0.6931/λ, where t1/2 is the half life and λ is the first order rate constant. The calculator below does this calculation using various time units.

Half Life/Rate Constant Converter

Half Life t 1/2 = 0.6931 / λ
t 1/2 = half life [T]
λ = rate constant [T -1 ]

Rate Constant (λ)

Half Life (t1/2)

Note: The rate constant is positive because the transport equation has the term - λ c The minus sign denotes loss of the contaminant to degradation.

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