To radiocarbon date an organic material, a scientist can measure the ratio of remaining Carbon-14 to the unchanged Carbon-12 to see how long it has been since the materials source died. Advancing technology has allowed radiocarbon dating to become accurate to within just a few decades in many cases.

How long is carbon dating accurate?

Because of the short length of the carbon-14 half-life, carbon dating is only accurate for items that are thousands to tens of thousands of years old. Most rocks of interest are much older than this. Geologists must therefore use elements with longer half-lives.