Rule of 72 Calculator

Enter an annual return rate to compare the Rule of 72 shortcut with exact annual-compounding doubling time.

Annual return (%)

Rule of 72 estimate

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ApproximationThe Rule of 72 is a shortcut, not an exact compounding identity. Exact annual-compounding time is shown for comparison.

How to use this Rule of 72 Calculator

Enter an annual percentage return to estimate doubling time with 72 divided by the percentage rate. The page also shows exact annual-compounding time for comparison.

What the result means

Enter an annual return rate to compare the Rule of 72 shortcut with exact annual-compounding doubling time.

Practical tips and limits

The Rule of 72 is a mental-math approximation. It becomes less accurate for very low or very high rates and does not model variable investment returns.