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Half-Life Calculator

Calculate decay values and convert between half-life parameters for exponential decay processes

How to Use This Calculator

Half-Life Value Calculator

Enter any 3 of the 4 values
Leave the 4th field empty
The calculator will automatically compute the missing value
Select appropriate time units for your calculation

Decay Parameter Converter

Enter any one parameter value
The other two will be calculated automatically
All parameters use the same time unit
Results show the mathematical relationships

This calculator uses the exponential decay formula: N(t) = N₀ × (1/2)^(t/t₁/₂) where N₀ is initial quantity, N(t) is remaining quantity, t is time elapsed, and t₁/₂ is the half-life.

Calculate Missing Value

Enter any 3 values to calculate the 4th in the exponential decay formula

Initial Quantity (N₀)

Remaining Quantity (N)

Time Elapsed (t)

Half-Life (t₁/₂)

Hours

Common Applications

Half-life calculations are used in various scientific fields

Physics & Chemistry

Radioactive decay calculations
Nuclear physics research
Dating archaeological specimens
Chemical reaction kinetics

Medicine & Biology

Drug metabolism and clearance
Biological half-life of substances
Medical isotope calculations
Environmental toxin degradation

Note: In real-world applications, decay processes may be affected by environmental factors, temperature, pressure, and other variables not accounted for in these ideal calculations.

Understanding Half-Life and Radioactive Decay

Half-life is the time required for half of a quantity of a radioactive substance to decay. It is a fundamental concept in nuclear physics, but it also appears in chemistry, environmental science, and pharmacology.

Half-Life Formula and Decay Constant

The standard formula N(t) = N0 × (1/2)^(t/t1/2) links initial quantity to remaining quantity after time t. Another expression uses decay constant λ: N(t) = N0 × e^(-λt).

Real-World Examples of Half-Life

Materials such as carbon-14 and uranium-238 decay over long periods, while medical isotopes decay over hours. The same idea also applies to metabolism and pollutant breakdown.

Using the Half-Life Calculator Effectively

Enter any three variables and the calculator computes the missing one instantly. Use it to convert between half-life, mean lifetime, and decay constant without manual algebra.

Whether you are analyzing radioactive decay, planning experiments, or studying persistence of chemicals, this calculator provides quick and reliable estimates.