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Rule of 72 Calculator
Estimate how long it takes an investment to double, or the rate needed to double it.
Free · No sign-up · Updated August 2026
Your money doubles in about
9.0 years
The Rule of 72 is a quick estimate: divide 72 by the annual rate to get the years to double (or vice versa). It's an approximation — most accurate for rates between 6% and 10%.
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Frequently asked questions
What is the Rule of 72?＋
A shortcut: divide 72 by the annual return to estimate the years for money to double (e.g. 72 ÷ 8% ≈ 9 years).
How accurate is it?＋
It's an approximation, most accurate for rates around 6-10%. For exact figures, use a compound interest calculator.