Rule of 72 Calculator
Use the Rule of 72 to quickly estimate how long it takes to double your money at any interest rate.
Use the Rule of 72 to quickly estimate how long it takes to double your money at any interest rate.
Your expected annual rate of return.
| Rate | Years to Double |
|---|---|
| 5% | 14.4 years |
| 6% | 12.0 years |
| 7% | 10.3 years |
| 8% | 9.0 years |
| 10% | 7.2 years |
| 12% | 6.0 years |
The Rule of 72 is a simple mental math shortcut: divide 72 by the annual rate of return to estimate how long it takes an investment to double. The exact answer uses the natural log formula: t = ln(2) / ln(1 + r).
Years to Double ≈ 72 / Annual Rate (%)The historical average stock market return is roughly 7–10% per year. At 8%, the Rule of 72 estimates your portfolio doubles in about 9 years. At 10%, it doubles in 7.2 years.
Credit card debt at 24% APR will double in just 3 years if left unpaid. The Rule of 72 makes this visceral — what works for investments works against you with debt.