Exponential Growth Calculator
Solve exponential growth and decay problems for the final amount, starting amount, rate or time.
About the Exponential Growth Calculator
Choose what to solve for (final amount, starting amount, rate or time) and the model (growth once per period, or continuous), then enter the other values. The calculator gives the answer, the doubling or halving time and a growth curve.
Exponential change multiplies by the same factor each period: populations, compound interest, bacteria, radioactive decay and depreciation. Use the discrete model when growth is applied once per period, and the continuous model (base e) for constant instantaneous growth.
The formula
A = A₀(1 + r)ᵗ or A = A₀e^(rt); doubling time = ln 2 ÷ ln(1 + r)
Worked example
1,000 growing 5% a period for 10 periods
- A = 1,000 × 1.05¹⁰
- = 1,628.89
- It doubles every 14.2 periods
Questions people ask
What's the rule of 70?
Doubling time ≈ 70 ÷ growth rate in %; at 5%, about 14 periods.
How do I model decay?
Use a negative rate, e.g. −10% per year.
Exponential or linear growth?
Linear adds the same amount each period; exponential multiplies by the same factor, so it speeds up over time.