Rule of 72 Calculator
Rule of 72 Calculator
Enter the expected annual interest rate or return.
What is the Rule of 72?
The Rule of 72 is a quick mental math shortcut to estimate how long it takes for an investment to double at a fixed annual rate of return. Simply divide 72 by the interest rate to get the approximate number of years.
For example, at 8% annual return: 72 ÷ 8 = 9 years to double your money. The actual time (using the exact logarithmic formula) is about 9.01 years — remarkably close.
This rule works well for rates between 6% and 10%. It becomes less accurate at very low or very high rates.
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