rule of 72 calculator
Rule of 72 Calculator to Estimate Investment Doubling Time
Rule of 72 is a quick mental model for compounding speed. This article explains where it works best and where it does not.
How to calculate using Rule of 72 Calculator
- Enter annual return to estimate years required to double capital.
- Or set target years and compute implied annual return required.
- Use it as a quick heuristic before detailed compounding analysis.
Rule of 72 Calculator formula
- Estimated years to double = 72 / annual return (%).
- Required return (%) = 72 / target years.
- Exact model uses logarithms and can differ slightly at extreme rates.
Worked example
- If annual return is 8%, doubling time is 72 / 8 = 9 years.
- If target is 6 years, required return is about 12%.
- Use compound-interest calculator for exact long-horizon planning.
Accuracy and interpretation notes
- Best used for moderate return ranges.
- Treat as estimate, not exact forecast.
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