Half-life calculator

Solve any one of initial amount, remaining amount, half-life, or elapsed time — given the other three.

N(t) = N₀ × (1/2)^(t / T)

Solves for the missing value using N(t) = N₀·(1/2)^(t/T). Units only need to be consistent — the same unit on both amounts and on both times. Leave the field you want to solve empty. Amounts share one unit; times share one unit.

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How to use

  1. Fill any three of the four fields.
  2. Leave the field you want blank.
  3. Calculate — the blank field is solved.

What it supports

Exponential decay Nt = N0·(1/2)^(t/T); any of the four variables can be the unknown. Values up to 1e15. One isotope/parent chain only — no decay chains or activity units.

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