Estimate the age of organic material using Carbon-14 decay. Enter the remaining C-14 percentage or activity ratio.
All living organisms absorb Carbon-14 from the atmosphere through food or photosynthesis. While alive, the ratio of C-14 to C-12 stays roughly constant. When the organism dies, it stops absorbing new carbon, and the C-14 it contains begins to decay with a half-life of 5,730 years. By measuring how much C-14 remains compared to what was originally present, you can estimate when the organism died.
Carbon dating is reliable up to about 50,000 years — beyond that, too little C-14 remains to measure accurately. The method also assumes that atmospheric C-14 levels have been constant, which isn't quite true. Calibration curves (based on tree rings, corals, and other records) are used to correct for these variations. Contamination from younger or older carbon sources can also skew results, which is why proper sample preparation is critical in any radiocarbon lab.