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
]
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.