Half-Life Calculator

Model exponential decay: remaining amount or half-life from two measurements.

Initial N0

Time t

Half-life

Calculated Result

Formula: N = N0 × 2^(−t/t½)

About this calculator

Radioactive decay and some drugs follow this model. Enter N0, time, and half-life — or N0, N, and time to solve t½.

FormulaN = N₀ × (1/2)^(t / t½) · t½ = t × ln2 / ln(N₀/N)

N = N0 × 2^(−t / t½). t½ = t × ln 2 / ln(N0 / N).

Calculate percentage change, percentage of values, and increase/decrease discounts instantly.

Advanced mathematical calculations with trigonometry, powers, roots, and logarithms.

Compute area of rectangles, circles, triangles, trapezoids, and ellipses.

Find radius, diameter, circumference, area, arc length, and sector area.