Half-Life Calculator

Estimate how much of a quantity remains after repeated half-life decay over time.

Preparing Half-Life Calculator

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Input

Enter the starting amount, the half-life, and the elapsed time to see how much of the material remains. You will see the result first and the step-by-step solution below.

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Step by Step Calculation

½t

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Calculate first and the full working will appear below automatically.

How to use Half-Life Calculator

Provide the initial quantity, the half-life interval, and the time passed, and the calculator will model the remaining amount after decay.

What this calculator is for

This calculator is for radioactive decay, medicine concentration estimates, chemical breakdown, and any process that shrinks by half over equal intervals.

Tips

Use matching time units for half-life and elapsed time.
The starting amount can be any unit as long as you keep it consistent.
Half-life models repeated halving, so each equal interval cuts the current amount, not the original amount, in half.