Half-Life Calculator

Calculate any parameter in radioactive decay equations

What to Calculate:

Time Unit:

Initial Amount (N₀):

Half-Life (years):

Elapsed Time (years):

Common Isotopes:

Half-Life Formulas

Decay Law: N(t) = N₀ × (1/2)^(t/t₁/₂) = N₀ × e^(-lambda×t)

Half-Life: t₁/₂ = ln(2)/lambda = t × ln(2)/ln(N₀/N)

Time: t = t₁/₂ × ln(N₀/N) / ln(2)

Initial: N₀ = N × 2^(t/t₁/₂)