What is the Rule of 72?

Divide 72 by the annual interest rate to find the approximate years to double your money: at 6%, 72÷6=12 years. At 9%, 72÷9=8 years. It works best for rates between 2–20%.

How accurate is the Rule of 72?

Very accurate for rates of 6–10%. For precise results use the exact formula: Years = ln(2)/ln(1+r). The Rule of 72 is typically within 1% of the exact answer in the 4–12% range.

Rule of 72 Compound Interest Calculator

Use the Rule of 72 to estimate how long it takes for an investment to double at a given interest rate, or what rate is needed to double in a target number of years.

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Enter the values for the scenario you are assessing. Use the Rule of 72 to estimate how long it takes for an investment to double at a given interest rate, or what rate is needed to double in a target number of years. Use the rule of 72 result to inform your calculation.

Rule of 72 Compound Interest Calculator

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What is the Rule of 72?

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