Rule of 72 Calculator
Estimate how long it takes to double an investment using the Rule of 72
Rate → Doubling Time
Enter the expected annual return, interest rate, or growth rate
Enter a rate to see doubling time
Target Time → Required Rate
How many years do you want your money to double in?
Enter target years to find the required rate
What is the Rule of 72?
Divide 72 by your annual return rate to estimate how many years it takes to double your money. Works best for rates between 6% and 10%.
Doubling Time Reference Table
| Rate (%) | Rule of 72 (years) | Exact (years) | Error |
|---|---|---|---|
| 1% | 72.0 | 69.66 | 3.4% |
| 2% | 36.0 | 35.00 | 2.8% |
| 3% | 24.0 | 23.45 | 2.3% |
| 4% | 18.0 | 17.67 | 1.9% |
| 5% | 14.4 | 14.21 | 1.4% |
| 6% | 12.0 | 11.90 | 0.9% |
| 7% | 10.3 | 10.24 | 0.4% |
| 8% | 9.0 | 9.01 | <0.1% |
| 9% | 8.0 | 8.04 | 0.5% |
| 10% | 7.2 | 7.27 | 1.0% |
| 12% | 6.0 | 6.12 | 1.9% |
| 15% | 4.8 | 4.96 | 3.2% |
| 18% | 4.0 | 4.19 | 4.5% |
| 24% | 3.0 | 3.22 | 6.9% |
Frequently asked questions
What does Rule of 72 Calculator do?
Estimate how long it takes to double an investment using the Rule of 72
What should I check in the result?
Check units, rates, dates and assumptions. Compare a simple case by hand before using the result for a decision.