What is the half-life of the carbon-14 isotope used in radiocarbon dating?

The half-life of carbon-14, the isotope used in radiocarbon dating, is about 5,730 years.

Carbon-14 is a radioactive isotope of carbon containing six protons and eight neutrons. It forms naturally in Earth’s upper atmosphere when cosmic-ray interactions produce neutrons that convert nitrogen-14 into carbon-14. Living organisms continually exchange carbon with their surroundings while alive.

After an organism dies, that exchange stops, and its carbon-14 gradually decays into nitrogen-14. Scientists compare the remaining carbon-14 with stable carbon isotopes to estimate when the organism stopped exchanging carbon. The method is especially useful for dating once-living material over timescales of thousands of years.

Radiocarbon dating is not suitable for every object or every age. Contamination, reservoir effects, calibration changes, and the method’s limited range can affect results. The half-life is sometimes rounded to 5,700 years, but 5,730 years is the commonly cited value.