Estimate age using carbon-14 decay.
Living tissue exchanges carbon with the atmosphere and holds a carbon-14 activity of about 15.3 disintegrations per minute per gram of carbon. Once the organism dies that exchange stops and the carbon-14 decays with a half-life of 5730 years. Measuring how much activity remains relative to a modern reference gives the number of half-lives that have passed, and multiplying by the half-life converts that into years.
Radiocarbon age
Age = half-life x log2(modern activity / sample activity); decay constant = ln 2 / half-life
Practically to about 50,000 years, roughly nine half-lives, at which point under 0.2 percent of the original carbon-14 remains and the signal is lost in background and contamination.
Published dates are calibrated. Atmospheric carbon-14 has varied over time, so raw ages are converted using tree-ring and coral calibration curves such as IntCal. This calculator gives the uncalibrated radiometric age.
The measured value is 5730 years, but conventional radiocarbon ages are still reported using Libby's original 5568-year half-life for historical consistency, then corrected during calibration. Set the field to whichever convention you need.