Does the unit of time matter?
As long as the "Time Elapsed" and "Half-Life" use the same unit (e.g., both in years or both in minutes), the calculation works.
Calculator
Enter your values
Results
Remaining Amount
50.0000
Amount Decayed
50.0000
% Remaining
50.00%
Decay Analysis
Radioactive decay progress
Decay Progress
Half-Lives Elapsed:1.00
Remaining Fraction:0.5000
Safety Interpretation
Significant decay has occurred, but a measurable amount remains.
Exponential Nature
Radioactive decay is exponential. It never theoretically reaches zero, but becomes statistically negligible. After 7 half-lives, less than 1% remains.
How to Use
Step-by-step instructions
- 1Enter the initial quantity (N0).
- 2Enter the time elapsed (t).
- 3Enter the half-life of the substance (t1/2).
- 4The calculator will compute the remaining amount.
Radioactive Decay
The amount of a radioactive substance decreases by half every half-life period.
N(t) = N0 x (1/2)^(t/t1/2)Variables:
N(t)Remaining quantityN0Initial quantitytTime elapsedt1/2Half-lifeExample
Carbon-14 Decay
Inputs:
Initial:100 g
Time:5730 years
Half-Life:5730 years
Steps:
- 1.t / t1/2 = 1
- 2.Remaining = 100 x (0.5)^1 = 50 g
Result:
50 g