General calculator
Rule of 72 calculator
A quick mental estimate; continuous compounding uses ln(2) more precisely.
Inputs
Enter valid numbers. Calculations run entirely in your browser.
Results
Approximate years to double
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Example
8% per year → about 9 years to double.
Explanation
Years ≈ 72 ÷ rate when rate is expressed as a percent.
FAQ
Negative rates?
Rule of 72 is for positive growth heuristics only.