Radiocarbon Dating Calculator

Carbon-14 has a half-life of 5730 years, meaning half of it decays over that period. This calculator uses that value to estimate sample age from the fraction of carbon-14 remaining.

It is generally reliable up to about 50,000 years. Beyond that, too little carbon-14 remains to measure accurately even with modern accelerator mass spectrometry, and trace contamination with recent carbon can produce significant errors.

Laboratory radiocarbon dates are calibrated against tree-ring records and marine sediment data to correct for historical variation in atmospheric carbon-14 levels. This calculator uses the raw decay formula without calibration, so it gives an uncalibrated estimate that may differ from an official calibrated date by decades to centuries for older samples.

No. It works only on organic materials that were once alive, such as bone, wood, charcoal, shell, and fabric. It cannot directly date pottery, stone, metal, or geological formations unless those materials contain trapped organic carbon.

The 5568-year value is the original Libby half-life measured in the 1940s. In 1962 a Cambridge conference recommended the more accurate 5730-year value, which this calculator uses. To keep decades of published dates comparable, radiocarbon laboratories still report conventional ages using the old 5568-year (Libby) half-life by convention, then apply calibration afterward. So a raw age from the 5730-year formula will differ by about 3% from a conventional lab age before calibration - the difference is a reporting convention, not a change in how fast carbon-14 actually decays.

An uncalibrated date (reported as radiocarbon years BP, or "RCYBP") comes straight from the decay formula and assumes atmospheric carbon-14 has always stayed constant. Because that level has actually drifted over time, labs convert the raw value into a calibrated date (written as "cal BP" or a calendar-year range) using curves such as IntCal that are anchored to tree rings and other dated records. The calibrated date is the true calendar age and is usually given as a range with a confidence level. This calculator returns an uncalibrated estimate, which can differ from a calibrated date by decades to a few centuries, so treat its output as a first approximation rather than a published archaeological date.