Rule of 72 Calculator
Use the Rule of 72 to quickly estimate doubling time β or what rate you need to double in a specific timeframe.
Years to Double
10.3 years
Rule of 72 Estimate
10.3 years
Exact Calculation
10.24 years
Doubled Amount
$20,000
Rule of 72: Years β 72 / Rate. Simple, accurate for rates between 2% and 15%.
What Is the Rule of 72?
Mental math shortcut: Years to Double β 72 / Rate. Accurate for rates between 2% and 15%.
Quick Reference
| Rate | Rule of 72 | Exact |
|---|---|---|
| 3% | 24.0yr | 23.4yr |
| 5% | 14.4yr | 14.2yr |
| 7% | 10.3yr | 10.2yr |
| 10% | 7.2yr | 7.3yr |
| 12% | 6.0yr | 6.1yr |
Reverse
Double in 5 years? Rate β 72/5 = 14.4%
Practical
- S&P 500 ~10%: doubles every 7.2yr
- Inflation 3%: costs double every 24yr