Rule of 72 Calculator
Estimate how many years it takes to double your money at a given rate of return using the Rule of 72, and compare it with the exact figure.
Your numbers
- Exact years to double
- 9.01 years
- Value after 4 doublings
- $160,000
How the rule of 72 calculator works
Years to double ≈ 72 ÷ rate. The exact figure is ln(2) ÷ ln(1 + rate).
Example
Using the default inputs (Annual rate: 8%; Starting amount: $10,000), the calculator returns years to double (rule of 72) of 9 years. Change any field above to see your own result and charts update instantly.
Good for these goals
Frequently asked questions
How accurate is the Rule of 72?
It is very close for rates between about 6% and 10%.
Can I use it for debt?
Yes. At 24% credit card APR, debt doubles in about three years if unpaid.
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Estimates are for educational purposes only and are not financial, tax or legal advice. Results depend on your inputs and simplified assumptions; tax figures reflect 2026 federal rules and may differ from your situation. See our disclaimer. © 2026 FinanzCalc.