Exponential Growth Calculator

Anything that grows by a fixed percentage per period — an investment, a bacterial colony, a user base — follows an exponential curve. Enter the starting value, the rate per period and the number of periods to get the final value, the total growth and the doubling time.

Results

Formula

Two standard models:
Discrete: Final = Start × (1 + r)t  ·  Continuous: Final = Start × ert
A negative rate produces exponential decay with the same formulas.

How to use this calculator

  1. Enter the starting value and the growth rate per period (use a negative rate for decay).
  2. Enter how many periods pass.
  3. Choose discrete or continuous growth, then Calculate.
Exponential Growth Calculator — how the calculation works, illustrated
Exponential Growth Calculator — how the calculation works, illustrated

Worked example

100 growing at 10% per period for 3 periods (discrete).

  1. Period 1: 110; period 2: 121; period 3: 133.10.
  2. Total growth: 33.10.

Result: The final value is 133.10, and at 10% the value doubles roughly every 7.27 periods.

Frequently asked questions

Discrete vs continuous — which fits my case?

Discrete fits interest credited or counts taken once per period (annual returns, yearly census). Continuous fits processes that compound constantly, like bacterial growth or continuously compounded interest.

What is doubling time?

How many periods the value needs to double at the current rate: ln(2) ÷ ln(1 + r) for discrete growth. The “Rule of 70” (70 ÷ rate%) approximates it quickly.

Does exponential growth go on forever?

Mathematically yes; in reality, limits (space, resources, market size) eventually bend the curve into an S-shape called logistic growth. Treat long projections as “if nothing changes” scenarios.

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