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Calculators / Finance / Rule of 72
Rule of 72 calculator
Compare a quick doubling-time estimate with the compound formula.
On this page
Approximate doubling time12years
Compound doubling time11.9years
Calculator controls
How to calculate
Compare a quick doubling-time estimate with the compound formula.
Approximate doubling time = 72/rate; Compound doubling time = ln(2)/ln(1+rate/100)
Worked example
Annual growth rate (%): 6.
Approximate doubling time: 12 years; Compound doubling time: 11.9 years.
Assumptions and limits
No. Its error changes with the rate. Neither value guarantees an investment outcome.
Results are rounded for display; calculations use unrounded values. Read our calculation methodology.
Understanding the result
The rule-of-72 shortcut is compared with doubling time under annual compounding at a constant positive rate.
When this tool is useful
Compare a quick doubling-time estimate with the compound formula.
Understanding your inputs
| Input | What to enter |
|---|---|
| Annual growth rate (%) | Enter a number of at least 0.000001 and no more than 100. |
Frequently asked questions
Is the shortcut exact?
No. Its error changes with the rate. Neither value guarantees an investment outcome.