Estimate the age of organic material from its remaining carbon-14, or the remaining fraction from an age, using the 5,730-year half-life.
Estimated age (years)
How to use this tool
Choose age from remaining carbon-14, or remaining carbon-14 from age.
Enter the remaining percentage or the age in years.
Check the half-life under Advanced options (default 5,730 years).
Read the result, remembering it is an uncalibrated textbook age.
Formula & worked example
A sample with 50% of its carbon-14 remaining is about 5,730 years old; at 25% remaining it is about 11,460 years old.
Limitations — read this before you rely on it
Uncalibrated textbook calculation only: no calibration curve, reservoir correction or contamination handling, so it will differ from a laboratory radiocarbon date.
Frequently asked questions
That is the conventionally used carbon-14 half-life for radiocarbon age calculation. An older Libby value of 5,568 years is sometimes seen in textbooks, but 5,730 is the standard here.
The sample started with the modern atmospheric carbon-14 ratio, gained or lost no carbon afterwards, and decayed undisturbed. Contamination or reservoir effects break these assumptions.
Atmospheric carbon-14 has varied over time, so raw radiocarbon years are converted with a calibration curve built from tree rings and other dated material.
Practically about 50,000 years; beyond that too little carbon-14 remains to measure reliably.
Once-living organic material — wood, charcoal, bone collagen, seeds and similar. Rocks and metals cannot be carbon dated.