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.
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, Mean Lifetime, and Decay Constant Conversion
Please provide any one of the following to get the other two.
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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
Applications:
- • Radioactive decay
- • Drug metabolism
- • Chemical reactions
- • Population decay
- • Carbon dating
- • Medical imaging
Common Half-Lives:
• Carbon-14: 5,730 years
• Uranium-238: 4.5 billion years
• Iodine-131: 8 days
• Technetium-99m: 6 hours
Variables:
- • t₁/₂: Half-life
- • τ: Mean lifetime
- • λ: Decay constant
- • N₀: Initial quantity
- • N(t): Quantity at time t
- • t: Time elapsed