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    Rule of 72 Calculator

    Calculate how long it takes to double your money with this free online rule of 72 calculator, or find the rate needed to double it in a set time.

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    How to use Rule of 72 Calculator

    1. 1Choose years to double or rate needed to double
    2. 2Enter your annual interest or return rate, or the number of years
    3. 3Compare the rule of 72 estimate with the exact answer and the time to triple or quadruple

    Frequently asked questions

    What is the rule of 72?▾

    It is a shortcut for compound growth: divide 72 by the annual rate to estimate how many years money takes to double. At 8% a year it doubles in about 9 years.

    How accurate is the rule of 72?▾

    It is very close for rates between 6% and 10%. At 8% the exact doubling time is 9.01 years against the estimate of 9. At very high rates it becomes less accurate.

    What is the rule of 69.3?▾

    It uses 69.3 instead of 72 and is exact for continuous compounding. The rule of 72 is used more often because 72 divides evenly by many common rates.

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