Rule of 72 Calculator
Estimate how many years it takes an investment to double at a given rate using the Rule of 72, compared with the exact answer.
Enter your values and press Calculate.
How to use the Rule of 72 calculator
The shortcut is most accurate for rates between about 6% and 10%.
Formula
Years to double ≈ 72 ÷ rate. Exact: ln 2 ÷ ln(1 + r).
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