Rule of 72 Math: Doubling Time Shortcut
Where 72 comes from, why it works (and when it doesn't), and how to apply it to every financial decision you make.
Read article →Rule of 72 Calculator
Estimate how many years it takes to double your money.
Understanding This Calculator
The Rule of 72 is a mental shortcut for doubling time. Divide 72 by your annual return to estimate how many years it takes for an investment to double in value.
Core Formula
Years to Double ≈ 72 / Annual Return (%)
How accurate is the Rule of 72?
It is most accurate for returns between 6% and 10%. Outside that range the Rule of 73 or logarithmic math is more precise.
Does inflation affect the rule?
Yes. Subtract the inflation rate from your nominal return to estimate real purchasing-power doubling time.
* All calculations above are theoretical estimates. Actual returns vary based on market performance, fees, taxes, inflation, and economic factors. This tool is for educational purposes only — not financial advice.
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