Exponential Decay Calculator
Calculate the final value of a quantity declining at a fixed percentage rate over a number of periods.
- Free to use
- No registration required
- Works on all devices
- Last updated
- 12-09-2026
Enter an initial value, decay rate, and number of periods to find the final value.
Your result
590.49
Final value
Total decline409.51
AI explanation
Formula
Final value = initial value × (1 − decay rate)^periodsWorked example
1000 decaying at 10% for 5 periods
| Field | Value |
|---|---|
| Initial value | 1000 |
| Decay rate per period (%) | 10 |
| Number of periods | 5 |
| Final value | 590.49 |
| Total decline | 409.51 |
Assumptions
- Uses discrete-period decay — the decay rate applies once per period, not continuously.
Frequently asked questions
What is exponential decay?
Decline where the decrease in each period is proportional to the current value — the quantity shrinks by the same percentage each period, so it never quite reaches zero.
What real-world quantities decay exponentially?
Radioactive decay, drug concentration in the bloodstream, and depreciating asset value (under a declining-balance method) are common examples.
How is this related to half-life?
Half-life describes a specific case of exponential decay where the decay rate is defined by how long it takes to lose half the quantity — see the Half-Life Calculator for that framing.