Exponential Decay Calculator
Calculate exponential decay. Enter starting value, decay rate per period and time to see remaining amount, amount decayed, half-life and a decay chart.
How to use this tool
- Enter initial value, decay rate per period and number of periods in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your remaining value and the full breakdown beneath it.
Exponential decay follows A = A₀(1 − r)^t, where A₀ is the initial amount, r the decay rate per period, and t the number of periods. The half-life is log(0.5) / log(1−r).
Frequently asked questions
- What is the difference between decay rate and half-life?
- The decay rate r is the fraction lost each period; the half-life is the number of periods until only half remains. They are linked by t½ = log(0.5)/log(1−r).
- Does this assume continuous or discrete decay?
- This calculator uses discrete (period-by-period) decay. For continuous decay use A = A₀·e^(−λt) with the half-life calculator.