By testing the amount of carbon stored in an object, and comparing to the original amount of carbon believed to have been stored at the time of death, scientists can estimate its age.

What affects the accuracy of carbon dating?

Factors affecting the accuracy of the carbon-dating method of analysis have been discussed by several workers (1, 3, 13, 14). The factors examined are: precision of analytical techniques, isotopic fractionation, incorporation of nuclear-bomb-produced Cl4 into humus, and contamination by re- use or soil-respired CO2.