Finance & Interest
Basic

Rule of 72

Approximate years to double an investment.

Formula

t≈72rt \approx \frac{72}{r}

Variables

rAnnual rate (%)
tYears to double

Example

72/6% ≈ 12 years

Did You Know?

Divide 72 by the interest rate to estimate the years for money to double — a startlingly accurate shortcut.

rule of 72doublinginterest