Doubling Rate Calculator (Rule of 72)

Verified formula Updated Jun 2026 Private — runs on your device

Verified formula Private

Required growth rate

9.00%

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

How to use the Doubling Rate Calculator (Rule of 72)

The Doubling Rate Calculator (Rule of 72) works out your required growth rate in an instant. Enter years to double 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.

Enter the years to double.
Read off your required growth rate — the calculator updates automatically, with no button to press.

Formula

The Doubling Rate Calculator (Rule of 72) uses the formula:

Required growth rate = 72 ÷ Years to double

Worked example

For example, with years to double of 8, the required growth rate is 9.00%.

Inputs used
Years to double	8

Results
Required growth rate	9.00%

Results are estimates for educational use, not professional advice.

Frequently asked questions

By the rule of 72, divide 72 by the years: 72 ÷ 8 = 9% a year.

The rule of 72 usually finds years from a rate; this reverses it to find the rate from the years.

It is a close approximation for moderate rates, handy for quick mental estimates.

72 ÷ 10 = 7.2% a year.

The Doubling Rate Calculator (Rule of 72) uses the formula: Required growth rate = 72 ÷ Years to double. For example, with years to double of 8, the required growth rate is 9.00%.

Enter the years to double. Read off your required growth rate — the calculator updates automatically, with no button to press.