Half-Life Calculator
Calculate half-life, mean lifetime, and decay constant for radioactive decay and exponential processes
Calculate half-life, mean lifetime, and decay constant for radioactive decay and other exponential decay processes.
About Half-Life
Half-life is the time required for a quantity to reduce to half of its initial value. It's commonly used in nuclear physics, chemistry, and medicine to describe radioactive decay, chemical reactions, and drug metabolism.
Key Formulas:
- N(t) = N₀ × (½)^(t/t₁/₂)
- t₁/₂ = ln(2) / λ
- τ = t₁/₂ / ln(2)
- λ = ln(2) / t₁/₂
Variables:
- • t₁/₂: Half-life
- • τ: Mean lifetime
- • λ: Decay constant
- • N₀: Initial quantity
- • N(t): Quantity at time t
Common Half-Lives:
- • Carbon-14: 5,730 years
- • Uranium-238: 4.5 billion years
- • Iodine-131: 8 days
- • Technetium-99m: 6 hours
Applications:
- • Radioactive decay
- • Drug metabolism
- • Chemical reactions
- • Carbon dating