Calculator Inputs
The page stays single-column, while the form fields shift to three columns on large screens, two on medium screens, and one on mobile.
Example Data Table
| Scenario | Isotope | Input Set | Method | Result |
|---|---|---|---|---|
| Ancient wood sample | Carbon-14 | Initial parent 100, current parent 25 | Age from parent remaining | 11,460 years |
| Fossil ratio study | Carbon-14 | Parent 20, daughter 60 | Age from daughter / parent ratio | 11,460 years |
| Radiometric count drop | Carbon-14 | Initial activity 1200, current activity 300 | Age from activity loss | 11,460 years |
| Decay projection | Uranium-238 | Prediction time 4.468 Gyr | Forward decay prediction | 50% parent remaining |
Formula Used
1) Parent decay law
N(t) = N0 * e^(-lambda * t)
N0 is initial parent amount, N(t) is remaining parent amount, lambda is the decay constant, and t is elapsed time.
2) Half-life and decay constant
lambda = ln(2) / T1/2
T1/2 = ln(2) / lambda
These formulas convert between half-life and decay constant so the calculator can accept either input style.
3) Age from parent remaining
t = ln(N0 / N) / lambda
Use this when you know the starting parent amount and the present parent amount after decay.
4) Age from daughter to parent ratio
t = ln(1 + D / P) / lambda
This assumes the daughter product came from radioactive decay and there was no initial daughter present.
5) Activity method
A(t) = A0 * e^(-lambda * t)
t = ln(A0 / A) / lambda
Activity falls with the same exponential rule as the number of unstable parent atoms.
How to Use This Calculator
- Select a calculation mode that matches your available data.
- Choose a preset isotope, or select Custom Isotope for your own decay values.
- Pick whether you want to enter half-life or decay constant.
- Set the output time unit for the final age or prediction.
- Enter your measured parent amount, daughter amount, or activity values.
- Add a contamination or background correction only if your lab process needs it.
- Press Calculate to show the result directly below the header and above the form.
- Use the CSV or PDF buttons to export the displayed result summary.
FAQs
1) What does radioactive dating estimate?
Radioactive dating estimates how long a sample has been decaying by comparing parent isotopes, daughter products, or activity changes against known decay behavior.
2) Why are isotope presets useful?
Presets speed up work and reduce typing mistakes because each isotope already includes a standard half-life commonly used in radiometric calculations.
3) When should I use the parent remaining mode?
Use it when you know the initial parent quantity and the current quantity. It works well for controlled examples and some laboratory reconstructions.
4) When is the daughter to parent ratio method better?
Choose the ratio method when both parent and radiogenic daughter amounts are available. It is common in geological dating workflows.
5) What does the contamination correction do?
It reduces the measured present signal by a chosen percentage. This can help approximate background removal or contamination adjustment during analysis.
6) Why does activity produce the same age trend?
Activity is proportional to the number of undecayed atoms, so it follows the same exponential decay law as parent quantity.
7) Can I enter a decay constant instead of half-life?
Yes. The calculator converts decay constant and half-life using natural logarithms, so both entry methods lead to the same decay model.
8) Does this replace full laboratory analysis?
No. It is a strong estimation tool, but real dating studies still need calibration, contamination controls, uncertainty analysis, and lab validation.