Every radioactive isotope is a ticking clock. Measure how much is left and read off the age — from a 3,000-year-old mummy to the 4.5-billion-year-old Earth.
Radiometric DatingLive
reading the atomic clock
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Radioactive isotopes decay at a fixed half-life, so the fraction remaining in a sample is a clock. Measure it and you can read the age: t = half-life × log₂(1/fraction). Carbon-14 dates organic material up to ~50,000 years; uranium-238, with a 4.5-billion-year half-life, dates the oldest rocks and the age of the Earth itself.
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How it works
Because a radioactive isotope decays with a fixed half-life, the fraction remaining in a sample encodes its age: t = half-life × log₂(1/fraction). Carbon-14 dates organic remains up to roughly 50,000 years, while long-lived potassium-40 and uranium-238 date rocks over millions to billions of years, anchoring the geologic timescale.
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The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.
Is this radiometric dating carbon-14 tool really free?▾
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The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.