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Rule of 72 Calculator
The Rule of 72 is a quick approximation for estimating the time it may take money to double at a steady annual growth rate. It is not a forecast and does not account for fees, taxes, volatility, or changing returns.
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Enter your own values. Results are estimates and may differ from financial institution disclosures.
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How this rule of 72 calculator works
Estimate how long an investment could take to double using the Rule of 72 and an assumed positive annual rate of return.
Approximate doubling time in years = 72 ÷ annual percentage rate.
Formula and assumptions
The calculation uses the values you enter and assumes the stated rate stays constant for the selected period. Actual account results can differ because of rate changes, timing, fees, taxes, rounding, deposits, withdrawals, or provider-specific rules.
Learn more about compound interest from the Consumer Financial Protection Bureau. Results are estimates and are not a promise of investment returns.
Frequently asked questions
Are these results guaranteed?
No. This tool provides an estimate based on your inputs. It does not guarantee a bank rate, investment return, or future purchasing power.
Can I use this calculator outside the United States?
Yes. Enter amounts in your preferred currency and interpret the result in that same currency. The calculator does not convert currencies or fetch live exchange rates.
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For education only. This calculator is not financial, tax, or investment advice.