Rule of 72 Calculator
Calculate rule of 72 from your own entered figures.
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Currency: Amounts are calculated in the currency you select; this site does not convert between currencies and does not use live exchange rates.
What this tool does
Calculate rule of 72 from your own entered figures. The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
How to use the Rule of 72 Calculator
- Enter or select annual return / interest rate (%).
- Read the calculated result; change any measurement to compare alternatives.
Formula
Rule of 72: years to double ≈ 72 ÷ rate; exact doubling time = ln(2)/ln(1 + rate)
- rate
- Annual return / interest rate (%)
The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
Worked example
For rule of 72 calculator, the following measurements illustrate the exact method: Annual return / interest rate (%): 8.
Inputs
- Annual return / interest rate (%)8
Result
- Years to double (Rule of 72)9
- Years to double (exact, compounded)9.01
- Years to quadruple (Rule of 72)18
Results explained
- Years to double (Rule of 72)
- Years to double (Rule of 72) from the formula above. The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
- Years to double (exact, compounded)
- Years to double (exact, compounded) from the formula above. The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
- Years to quadruple (Rule of 72)
- Years to quadruple (Rule of 72) from the formula above. The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
Frequently asked questions
Rule of 72: years to double ≈ 72 ÷ rate; exact doubling time = ln(2)/ln(1 + rate)
The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.
No. All numbers are entered by you or come from the dated reference table shown on this page; calculations run locally.
This is an estimate, not financial, tax or legal advice. Verify the inputs and output with official sources and a qualified professional.
Check period consistency, currency, percentage inputs and the assumptions: The Rule of 72 is a mental-math approximation, most accurate near 6–10% with annual compounding; the exact figure is shown alongside.