Rule of 72 Calculator
Estimate how long it may take an investment to double at a given annual rate of return using the Rule of 72.
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Estimated Result
How the Rule of 72 works
The Rule of 72 is a quick estimation method for understanding how long it may take an investment to double at a steady annual rate of return.
For example, at an 8% annual return: 72 ÷ 8 = 9 years.
How to use this calculator
What to enter
Enter or select the following as requested: Annual Rate of Return (%). Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The Rule of 72 gives an approximate number of years for money to double by dividing 72 by the annual percentage growth rate. It is a shortcut for steady compounding, not an exact projection, especially at very high or changing rates.
When to use it
Use this for a quick comparison of how different annual growth or interest rates affect approximate doubling time. For an actual savings or investment forecast, use the stated rate, compounding schedule, fees, taxes, and contribution timing.