Half-Life Calculator

Calculate radioactive decay using the half-life formula.

What to Calculate
Parameters

Starting quantity

Time for half to decay (e.g., 5730 years for C-14)

Time since initial measurement

Half-Life Formula

N = N₀ × (1/2)^(t/t½)

Variables:

  • N = Remaining amount
  • N₀ = Initial amount
  • t = Time elapsed
  • t½ = Half-life

Common Half-Lives:

  • Carbon-14: 5,730 years
  • Uranium-238: 4.5 billion years
  • Radon-222: 3.8 days

Related Calculators

Half-Life Result
Remaining Amount29.8292
Percent Remaining29.8292%
Amount Decayed70.1708
Number of Half-Lives1.7452
Decay Constant (λ)0.0001