Free Half-Life Calculator
Calculate half-life from initial amount, remaining amount, and elapsed time.
years
Half-Life
5,730.00 years
Decay Constant0.00012097 1/year
Half-Life vs Time Elapsed
Half-Life Determination
The half-life can be computed from measured decay data.
Formula
t_half = -t * ln(2) / ln(N/N_0)
The decay constant is lambda = ln(2) / t_half. This connects the exponential decay rate to the half-life.
Example Calculation
A sample starts at 100 units and has 25 remaining after 11,460 years.
- 01t_half = -t * ln(2) / ln(N/N0)
- 02t_half = -11460 * 0.6931 / ln(25/100)
- 03t_half = -11460 * 0.6931 / (-1.3863)
- 04t_half = 7940 / 1.3863
- 05t_half = 5730 years (Carbon-14)
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