Carbon Dating Estimate Calculator

Estimated Result

Raw radiocarbon estimate. Calibration is not applied automatically.

Enter values below

Complete the form and select Calculate Estimate to view age, decay values, uncertainty, and report options.

Calculator Inputs

Calculation Mode

Sample Name

Laboratory ID

Material Type

Site / Context

Calibration Reference

Measurement Type

Measurement Value

Percent modern carbon uses values from 0 to 100.

Assumed Initial Ratio

Age in Years BP

Carbon-14 Half-life

Custom Half-life

Relative Measurement Uncertainty (%)

Sample Notes

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Sample	Material	Measurement	Fraction Modern	Age BP	Uncertainty Range	Calendar Display	Calibration Ref.	Action

Formula Used

Age from remaining carbon: t = -ln(N/N₀) / λ

Decay constant: λ = ln(2) / half-life

Reverse calculation: N/N₀ = e^-λt

How to Use This Calculator

Select whether you want age estimation or reverse calculation.
Enter sample information and choose the measurement format.
Select the desired carbon-14 half-life or enter a custom value.
Add relative measurement uncertainty when available.
Select a calibration reference for documentation only.
Calculate the result and review formulas warnings and age ranges.
Add samples to history for comparison and export them.

Carbon-14 Decay Reference Table

Half-lives	Approximate Age	C-14 Remaining	Fraction Modern
0	0 years	100%	1.0000
1	5,730 years	50%	0.5000
2	11,460 years	25%	0.2500
3	17,190 years	12.5%	0.1250
4	22,920 years	6.25%	0.0625
5	28,650 years	3.125%	0.03125
8	45,840 years	0.390625%	0.00390625

Understanding Carbon Dating Estimates

Radiocarbon dating estimates age by measuring radioactive carbon-14 remaining in organic material. Living organisms exchange carbon with their environment while alive. After death that exchange stops and carbon-14 begins predictable radioactive decay. The calculator compares remaining carbon-14 with an assumed starting level. It then applies the selected half-life to estimate elapsed time. A commonly used half-life is 5,730 years for carbon-14. Some conventional calculations use the older 5,568-year Libby value. Changing the half-life changes the reported age slightly.

How the Calculation Works

Radioactive decay follows an exponential relationship rather than a linear decrease. Half of the original carbon-14 remains after one half-life. One quarter remains after two half-lives. The calculator converts your measurement into a remaining fraction first. It then uses the natural logarithm decay equation for age. Reverse mode performs the opposite calculation from a supplied age. It estimates the expected fraction and percentage of carbon-14 remaining. Relative measurement uncertainty can also produce an approximate age range.

Interpreting Results Carefully

Radiocarbon age is normally reported in years Before Present or BP. The conventional reference year for BP is 1950. A simple BCE or CE conversion is only an approximate display. Laboratory radiocarbon ages often require calibration against chronological records. Curves such as IntCal20 can adjust radiocarbon ages into calendar ranges. This calculator can store a calibration reference but does not perform calibration. Marine samples can require reservoir corrections before calendar interpretation.

Limits and Good Practice

Very old samples contain little measurable carbon-14 and become harder to date. Practical limits often approach about fifty thousand years. Contamination can make a sample appear younger or older. Record sample type laboratory identifiers context and preparation notes whenever possible. Treat results as educational estimates rather than laboratory determinations. Professional dating should include uncertainty calibration contamination review and sample-specific corrections.

Frequently Asked Questions

What does years BP mean?

BP means Before Present. Radiocarbon convention uses 1950 as the reference year.

Why are two carbon-14 half-lives offered?

The modern physical half-life is about 5,730 years. Conventional radiocarbon reporting historically used the 5,568-year Libby value.

Does the calculator calibrate radiocarbon ages?

No. Calibration references are stored with the report, but no calibration curve transformation is applied.

How accurate is the estimate?

Accuracy depends on measurement quality, contamination, pretreatment, reservoir effects, calibration, and sample context.

What is the useful age range?

Routine radiocarbon dating becomes difficult as samples approach roughly fifty thousand years because very little carbon-14 remains.

Can marine or shell samples need special corrections?

Yes. Marine reservoir effects can shift apparent ages and may require specialized correction before calendar interpretation.

Scientific Disclaimer

This calculator provides educational estimates only. Laboratory measurement calibration reservoir corrections contamination analysis and expert archaeological interpretation may materially change a final date.