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Radioactive Decay calculator
Radioactive Decay calculator
Enter your values below and press Calculate to see your result instantly.
Remaining Nuclei (Nβ)
297.8
DECAY CONSTANT (Ξ»)
0.00012
MASS LOSS
70.2%
After 10,000 units of time, only 29.7% of original matter remains active.
About the Radioactive Decay calculator
Calculate how much of a radioactive isotope remains after a period of time, using a custom half-life or a common isotope.
How to use the Radioactive Decay calculator
- Enter the Initial Quantity (Nβ) and choose a Predefined Isotope or enter a custom Half-Life (tΒ½).
- Enter the Time Elapsed (t).
- Press Calculate.
Formula and method
N(t) = Nβ Γ (Β½)^(t Γ· tΒ½). Half-lives: carbon-14 about 5,730 years, uranium-238 about 4.47 billion years, caesium-137 about 30 years and iodine-131 about 8 days.
Worked example
A sample that has 25% of its original carbon-14 is two half-lives old: about 11,460 years.
Tips
- Use the same time unit as the half-life.
- Carbon dating works for organic material up to roughly 50,000 years old.
Frequently Asked Questions
Living things absorb it, and after death it decays at a known rate, which lets scientists work out the age.