What is radioactive decay half-life?

Half-life (t½) is the time required for exactly half of the radioactive atomic nuclei of a given isotope to undergo spontaneous decay into daughter elements.

What is the decay constant (lambda)?

The decay constant (λ) measures the probability per unit time that a nucleus will decay: λ = ln(2) / t½ ≈ 0.693147 / t½.

PHYSICS & CHEMISTRY

Radioactive Decay & Elimination Half-Life Calculator

Solve radioactive decay equations: calculate remaining quantity, decay constant (λ), and elapsed time using exponential decay kinetics.

Initial Quantity (N₀)

Half-Life (t½ in years/hours)

Elapsed Time (t)

Decay Results

25.00

Remaining Quantity N(t)

Quantity Decayed

75.00 (75.0%)

Number of Half-Lives

2.00

Decay Constant (λ)

0.1315