All calculatorsRadiocarbon Dating Calculator (Carbon-14)
Estimate a sample’s age in years BP (Before Present = 1950) using Carbon-14 decay. Enter a fraction remaining, % modern carbon, or an activity ratio.
Background
Carbon-14 decays exponentially. If you know how much C-14 remains compared to “modern” carbon, you can estimate the time since the organism stopped exchanging carbon with the environment.
How to use this calculator
- Pick an input type: F, pMC, or A/A₀ (or convert age → F).
- Choose a Carbon-14 half-life (5730, 5568, or custom).
- Click Calculate to get the age in years BP.
How this calculator works
- Converts your input into a fraction remaining F.
- Computes λ = ln(2) / t½.
- Computes age: t = − ln(F) / λ.
Formula & Equation Used
Decay constant: λ = ln(2) / t½
Age (years): t = − ln(F) / λ
Note: This is an idealized radiocarbon age estimate (not a calibrated calendar age curve).
Example Problems & Step-by-Step Solutions
Example 1 — F = 0.50
With a half-life of 5730 years, F = 0.5 gives t ≈ 5730 BP.
Example 2 — pMC = 25%
F = 0.25 is about two half-lives → t ≈ 11460 BP (using 5730).
Example 3 — Convert age → fraction remaining
If t = 5730 BP, then F ≈ 0.5.
Frequently Asked Questions
Q: What does “years BP” mean?
BP means “Before Present,” where “present” is defined as the year 1950.
Q: What’s the difference between 5730 and 5568 years?
5730 is the modern commonly used half-life; 5568 is the historical Libby value.
Q: Is this the same as calibrated calendar age?
No. Calibration uses curves and additional corrections; this gives the basic decay-based estimate.
