Half-Life Calculator

Calculate half-life, remaining amount, time elapsed, and decay constant for radioactive decay with step-by-step solutions.

Calculator

Time units (years, days, hours, etc.)

Same time units as half-life

Select a calculation type and enter the required values to calculate half-life, remaining amount, time elapsed, or initial amount.

Complete User Guide

What is Half-Life?

Half-life is the time required for half of a quantity of a radioactive substance to decay. It's a constant that characterizes the rate of exponential decay.

The formula for exponential decay is: N = N₀ × e^(-λt), where N is the remaining amount, N₀ is the initial amount, λ is the decay constant, and t is time.

Calculation Types

  • Remaining Amount: Calculate how much remains after a given time
  • Time Elapsed: Calculate how long it took to reach a certain remaining amount
  • Initial Amount: Calculate the original amount before decay
  • Half-Life: Calculate the half-life from initial and remaining amounts

Examples

Example: Carbon-14 Decay

Half-Life: 5730 years

Initial Amount: 100 g

Time Elapsed: 11460 years (2 half-lives)

Remaining Amount: 25 g (25% of original)

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