• Home
• Financial Calculators
• Weight Loss Calculators
• Math Calculators
• Pregnancy Calculator
• Others

Half Life Calculator

The following tools can generate any one of the values from the other three in the half-life formula for a substance undergoing decay to decrease by half.

Half Life Calculator

Please provide any three of the following to calculate the fourth value.

Half Life, Mean Lifetime, and Decay Constant Conversion

Please provide anyone of the following to get the other two.

Definition and Formula

By definition, half-life is the period of time it takes for a substance undergoing decay to decrease by half. An exponential decay process can be described by any of the following three equivalent formulas:

N_t = N₀(1/2)^t/t_1/2
N_t = N₀e^-t/τ
N_t = N₀e^-λt

where
    N₀ is the initial quantity
    N_t is the quantity that still remains after a time t,
    t_1/2 is the half-life
    τ is the mean lifetime
    λ is the decay constant

t_1/2 = ln(2)τ = ln(2)/λ