Rule of 72 Calculator
Approximation, not an exact compounding calculation.
Approximate doubling time = 72 ÷ annual rate (%)
Estimate a doubling time using the Rule of 72 approximation.
Formula
Approximate doubling time = 72 ÷ annual rate (%)
Worked example
Annual growth rate: 6 %
With these inputs, the result is 12 years. Approximation, not an exact compounding calculation.
How to use this calculator
- Identify the quantity you want to calculate.
- Enter your measurements in the units shown on each field.
- Read the result, which updates as you change the inputs.
- Check the assumptions below before applying the result.
Assumptions and limits
Assumes constant positive growth. Accuracy varies with the growth rate.
Precision and checking
Results are rounded for display. Use the most accurate measurements available, and avoid rounding your inputs unnecessarily. Extra decimal places in a result do not make an estimate more reliable.
To check a result, substitute the same input values into the formula shown above. Change one value at a time to understand how the quantity responds.
Frequently asked questions
What assumptions does this calculation use?
Assumes constant positive growth. Accuracy varies with the growth rate.
Are my inputs sent to a server?
No. The calculation runs locally in your browser. The result updates as you edit the inputs.
Sources & references
- Compound Interest Calculator — U.S. Securities and Exchange Commission
