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Doubling Time Calculator

Verified formula Updated Jun 2026 Private — runs on your device

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Verified formula Private

Doubling time (periods)

10.24

Rule of 72 estimate
10.29

For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.

How to use the Doubling Time Calculator

The Doubling Time Calculator works out your doubling time (periods), along with 1 related figure in an instant. Enter growth rate per period and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.

  1. Enter the growth rate per period.
  2. Read off your doubling time (periods), together with rule of 72 estimate — the calculator updates automatically, with no button to press.

Worked example

For example, with growth rate per period of 7%, the doubling time (periods) is 10.24.

Inputs used
Growth rate per period 7%
Results
Doubling time (periods) 10.24
Rule of 72 estimate 10.29

Results are estimates for educational use, not professional advice.

Frequently asked questions

Use ln(2) ÷ ln(1 + rate). At 7% growth, the exact doubling time is about 10.24 periods.

Dividing 72 by the rate gives a quick estimate — about 10.3 at 7% — which is very close to the exact figure for typical rates.

Investments, populations, savings, inflation — anything that grows at a steady percentage rate per period.

No. The result is in whatever period the rate is per — years, months or days — as long as the rate matches that period.

Enter the growth rate per period. Read off your doubling time (periods), together with rule of 72 estimate — the calculator updates automatically, with no button to press.

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