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Free nuclear decay calculator for half-life based radioactive decay modeling. Estimate decay constant, remaining quantity, and activity at any elapsed time.
Last updated: April 20, 2026
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Remaining quantity N(t)
268.4019
Decay constant lambda
0.131527
Decayed quantity (N0 - N)
731.5981
Activity at time t
35.3021
Initial activity A0
131.5270
Interpretation
Remaining quantity is 268.4019 after 10.00 time units with activity 35.3021 per time unit.
Model note:
Assumes pure exponential first-order radioactive decay with constant half-life.
Formula
lambda = ln(2) / T1/2
Model
N(t) = N0 exp(-lambda t)
Relation
A = lambda N
N0=1000, T1/2=5.27, t=10 (same time units)
Remaining quantity
268.4019
Activity at t
35.3021
The calculator models first-order radioactive decay, where the proportion decaying per unit time is constant. It translates half-life into decay constant, then computes amount remaining and activity over elapsed time.
lambda = ln(2) / T1/2N(t) = N0 exp(-lambda t)A(t) = lambda N(t)Keep half-life and elapsed time in the same unit basis for consistent results.
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