Chemistry
Half-Life Calculator
Calculate radioactive decay and kinetics
Half-Life Formula
Exponential Decay Law
N = N₀ × (1/2)^(t / t₁/₂)
Or equivalently: N = N₀ × e^(-λt)
Decay Constant Relation
λ = ln(2) / t₁/₂ ≈ 0.693 / t₁/₂
Links half-life to decay constant
N = Remaining quantity
N₀ = Initial quantity
t = Time elapsed
t₁/₂ = Half-life
λ = Decay constant
Common Half-Lives
Carbon-145,730 years
Uranium-2384.5 billion years
Iodine-1318.02 days
Radon-2223.82 days
Technetium-99m6 hours
Caffeine (body)5-6 hours
Disclaimer
Half-life calculations assume ideal exponential decay. Actual decay behavior may vary due to environmental or system-specific factors. For medical or safety-critical applications, consult professional resources.