HalfLife: Decay Calculator

Turn a half-life, a starting amount and an elapsed time into the amount left, the percent remaining, the decay constant and a decay curve you can read at a glance. Four calculators in one app. • Decay: solve for the remaining amount, the elapsed time or the half-life itself • Activity: convert mass, moles, atoms and activity (Bq, Ci) of a radionuclide, with specific activity • Dosing: repeated doses with first-order elimination, from accumulation to steady-state peak and trough (a mathematical model, not medical advice) • Growth: final amount, doubling time or time to a target • Sixteen isotope presets with NUBASE2020 half-lives, from technetium-99m and iodine-131 to carbon-14 (Cambridge and Libby values) and uranium-238 • Times from seconds to billions of years, with scientific notation for huge or tiny values • Milestones at 1, 2, 3, 4, 5 and 10 half-lives • Save scenarios you check often and share results Useful for radiocarbon dating exercises, tracer and lab work, and physics or chemistry homework. Results are for education and reference only; real dating needs calibration.