Rule of 72 Calculator
How long money takes to double.
Enter your values
ⓘ Live results
Results
- Years to double (rule of 72)
- 9
- Exact years
- 9.01
- Value after doubling
- $20,000.00
- Value in 20 years
- $46,609.57
- Doublings in 30 years
- 3.33
Quick answer
Divide 72 by the annual return to approximate the years needed to double your money.
Years to double ≈ 72 ÷ Rate
How to use the Rule of 72 Calculator
- 1Enter your expected annual return.
- 2Optionally enter a starting amount.
- 3Compare the shortcut to the exact answer.
Worked example
Using the values the calculator loads with:
Inputs
- Annual return8 %
- Starting amount10000 $
Results
- Years to double (rule of 72)9
- Exact years9.01
- Value after doubling$20,000.00
- Value in 20 years$46,609.57
- Doublings in 30 years3.33
Frequently asked questions
Why 72?
It divides cleanly and closely matches the logarithmic answer for rates between 6% and 10%.
When is it inaccurate?
At very high or very low rates — use 69.3 for continuous compounding.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.