How to use the Half-Life Calculator
Estimate remaining amount from initial amount, elapsed time, half-life with the Half-Life Calculator. It includes Remaining amount, Elapsed time, Half-life, Initial amount, Half-life from decay constant, Decay constant from half-life workflows, so choose the one that matches the values you actually know. Use it to check the arithmetic while keeping the displayed method and entered values with your work.
Step by step
- For the Half-Life example, select Remaining amount and enter initial amount, elapsed time, half-life. Keep each value in the unit displayed beside its field.
- Review the selected Half-Life workflow and inputs, then read remaining amount in the result panel.
- Change one Half-Life assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.
How the calculation works
Solves A = A₀ × (1/2)^(t/t½) and converts t½ = τ ln(2) = ln(2)/λ.
Worked example
To reproduce the Half-Life worked example, reset the calculator. Select the Remaining amount workflow. Use initial amount 100; elapsed time 12 day; half-life 4 day. The result is remaining amount of 12.5. Remaining amount: Solves A = A₀ × (1/2)^(t/t½) and converts t½ = τ ln(2) = ln(2)/λ. Review the displayed units before comparing the result.
Understanding the result
The Half-Life reports remaining amount. Use it to check the arithmetic while keeping the displayed method and entered values with your work. The result depends on the entered values, selected mode, and displayed mathematical assumptions.
How to check the answer
Check the Half-Life answer by substituting remaining amount back into the stated relationship. Test a simple value such as zero, one, or an equal pair, then confirm that sign, scale, units, and rounding match Solves A = A₀ × (1/2)^(t/t½) and converts t½ = τ ln(2) = ln(2)/λ.
Common questions
What does the Half-Life calculate?
Estimate remaining amount from initial amount, elapsed time, half-life with the Half-Life Calculator.
Which inputs does the Half-Life example use?
The worked example uses initial amount, elapsed time, half-life in the Remaining amount workflow. Other workflows can show different fields. Keep the chosen workflow and units with the result when comparing calculations.
Is the Half-Life result exact?
The result depends on the entered values, selected mode, and displayed mathematical assumptions. Recheck initial amount, elapsed time, half-life and use remaining amount only for a decision where that level of precision is appropriate.