basic

Radioactive Decay Remaining Mass Fraction Calculator

N(t) = N₀ · exp(−λ·t), λ = ln 2 / t½.

Compute the fraction of an unstable isotope remaining after time t given the half-life t½: fraction = exp(−ln(2) · t / t½). Reports the decay constant λ = ln 2 / t½, the surviving mass fraction, and the remaining and decayed masses for a given starting amount.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

days
days
g

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

N(t)/N₀ = exp(−ln 2 · t / t½).

In depth

Compute the fraction of an unstable isotope remaining after time t given the half-life t½: fraction = exp(−ln(2) · t / t½). Reports the decay constant λ = ln 2 / t½, the surviving mass fraction, and the remaining and decayed masses for a given starting amount.