Rule of 72 Calculator
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years
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years
Formula: Years ≈ 72 / Interest Rate
Years ≈ 72 / Interest Rate
Step-by-Step Examples
7% annual return = ~10.29 years
72 / 7 = 10.29
Frequently Asked Questions
What is the Rule of 72?
A quick mental math shortcut to estimate how many years it takes to double an investment at a fixed annual return.
How accurate is the Rule of 72?
Very accurate for rates between 6-10%. For lower or higher rates, the Rule of 69.3 or Rule of 70 may be more precise.