Financial calculators
Rule of 72
Estimate how long a constant rate could take to double an amount.
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Approximate time to double
12.0 years
At a hypothetical constant annual rate of 6%.
Rule of 7272 ÷ 6
Exact annual compounding11.9 years
This shortcut is an approximation, not a prediction of future investment returns.
Methodology and assumptions
The Rule of 72 divides 72 by a positive annual percentage rate. The comparison uses ln(2) ÷ ln(1 + r), with r expressed as a decimal, assuming annual compounding.
For general education only. These materials do not provide personalized investment, insurance, tax, or legal advice. Actual outcomes vary, and investments may lose value.