Half-Life Calculator
Calculate half-life and radioactive decay
Enter Decay Information
Half-Life Results
About This Calculator
The Half-Life Calculator helps you calculate the half-life of a substance based on initial and remaining amounts over time. Half-life is the time required for half of a radioactive substance to decay, and is used in chemistry, physics, and medicine.
This tool is essential for students, researchers, and professionals working with radioactive decay, pharmacokinetics, or any exponential decay processes. The calculator uses the standard half-life formula to determine decay characteristics.
Formula & Calculation Method
Half-life calculations use the formula:
N(t) = N₀ × (1/2)^(t/T)
T = t / log₂(N₀/Nt)
λ = ln(2) / T
Where:
- N(t) = Remaining amount after time t
- N₀ = Initial amount
- t = Time elapsed
- T = Half-life
- λ = Decay constant
How to Use This Calculator
Frequently Asked Questions
What is half-life?
Half-life is the time required for half of a radioactive substance to decay. It is a constant characteristic of each radioactive isotope and is used to measure decay rates.
How is half-life used?
Half-life is used in radioactive dating (carbon-14 dating), medical imaging (radioactive tracers), nuclear physics, pharmacokinetics (drug elimination), and environmental science.
What is the decay constant?
The decay constant (λ) is the probability per unit time that a nucleus will decay. It is related to half-life by: λ = ln(2) / T, where T is the half-life.
Can half-life be different for different substances?
Yes, each radioactive isotope has a unique half-life ranging from fractions of a second to billions of years. For example, carbon-14 has a half-life of about 5,730 years.
Calculator by
NumCalculators Editorial Team
Multi-disciplinary Expert Team