Half-Life Calculator
Calculate radioactive decay and the remaining amount of an isotope after a given time.
Common isotopes
Remaining amount
25.0000
25.00% remaining
Number of half-lives
2.00
Decay constant (λ)
1.2097e-4
Decay curve
11082,55527,50
Formula
N(t) = N₀ × (1/2)^(t/t½)
N(t) = Amount remaining at time t
N₀ = Initial amount
t = Time elapsed
t½ = Half-life
What is half-life?
Half-life is the time required for half of the atoms in a radioactive sample to decay. It's a characteristic property of each isotope.
Decay formula
N(t) = N₀ × (1/2)^(t/t½). After each half-life, exactly half of the original substance remains.
Applications
Half-life is used in radiometric dating (like carbon-14), nuclear medicine, radiation safety, and nuclear waste treatment.