Time to Double Calculator
Use the Rule of 72 to find how long it takes to double your money at any interest rate, or what rate you need to double in a given time. Includes comparison table for common rates.
How Long to Double Your Money?
Rule of 72: Divide 72 by the interest rate to estimate how many years it takes to double your money. At 7%, roughly 72/7 = 10 years.
Time to Double
10.24 years
at 7.00% annual interest
Time to Double at Various Rates
| Annual Rate | Time to Double | Rule of 72 |
|---|---|---|
| 1% | 69.66 years | 72.00 years |
| 2% | 35.00 years | 36.00 years |
| 3% | 23.45 years | 24.00 years |
| 4% | 17.67 years | 18.00 years |
| 5% | 14.21 years | 14.40 years |
| 6% | 11.90 years | 12.00 years |
| 7% | 10.24 years | 10.29 years |
| 8% | 9.01 years | 9.00 years |
| 10% | 7.27 years | 7.20 years |
| 12% | 6.12 years | 6.00 years |
| 15% | 4.96 years | 4.80 years |
| 20% | 3.80 years | 3.60 years |
About the Rule of 72
The Rule of 72 is a quick way to estimate how long an investment takes to double. Divide 72 by the annual interest rate.
Formula: Years to Double = 72 / Annual Rate. The actual formula is more precise: Years = ln(2) / ln(1 + r), but Rule of 72 gives a good approximation for rates between 1% and 10%.
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