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Rule of 72 Calculator
Result
Chart
Show formula & working
Years to double ≈ 72 ÷ rate · triple ≈ 114 ÷ rate · quadruple ≈ 144 ÷ rate
Exact: ln(multiple) ÷ ln(1 + rate)
Details
How this works
A quick mental shortcut: divide 72 by the annual return to get the years to double. It is most accurate around 6%–10%.
The same idea works for inflation: at 6%, prices double in about 12 years.
Frequently asked questions
Why 72?
It is close to 100 × ln 2 (69.3) and divides easily by many numbers.
Is it accurate at high rates?
Less so; the exact figure is shown alongside.