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Free half-life calculator for radioactive decay and exponential reduction problems. Estimate remaining amount, decayed quantity, decay constant, and elapsed half-lives with instant results.
Last updated: April 20, 2026
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Remaining amount
18.946
Decayed amount
81.054
Decay constant
0.13863
% remaining
18.95%
Half-lives elapsed
2.400
Interpretation
After 12.000 time units, about 18.946 units remain (18.95%).
Formula:
N(t) = N0 × (1/2)^(t / T1/2)
Formula
N(t) = N0(1/2)^(t/T1/2)
Relation
lambda = ln(2) / T1/2
Metric
t / T1/2
N0 = 100, T1/2 = 5, elapsed t = 12
Remaining amount
18.95
% remaining
18.95%
The calculator applies exponential decay equations using half-life as the governing parameter. It returns both remaining and decayed quantities along with useful derived metrics for interpretation.
N(t) = N0 × (1/2)^(t/T1/2)lambda = ln(2)/T1/2These relations are widely used in nuclear physics, pharmacokinetics, and decay-based process modeling.
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