Remaining amount after a time, or sample age from what remains, with a ¹⁴C half-life default.
| N(t) or age | – |
| λ | – |
Use this calculator in a counting lab or a carbon-14 homework when you know half-life and either elapsed time or remaining amount.
The calculation is λ = ln 2 / t½. Remaining mode: N = N₀ e^(−λt). Age mode: t = ln(N₀/N) / λ. Use the same time unit for half-life and t. The default 5730 y is Libby ¹⁴C; there is no calibration curve.
This is a single-exponential decay. It does not include branching, a mixture of nuclides, or radiocarbon calibration.
Mode: N after time t, or age from the remaining N.
Half-life: Half-life in years, days, or seconds, same unit as time. ¹⁴C default is 5730 years.
N0: Starting amount: counts, moles, or grams. 1 if you only care about the fraction left.
t or remaining N: Elapsed time (same unit as half-life) or remaining N, depending on the mode.
N(t) or age: Remaining amount, or elapsed time in the half-life unit.
λ: Decay constant in 1/(half-life unit).
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