Rule of 72 Calculator
Quickly estimate how many years it will take to double your investment at a given interest rate. Also see tripling time (Rule of 114) and quadrupling time (Rule of 144).
Rule of 72 Calculator
FAQ
What is the Rule of 72?
The Rule of 72 is a quick mental math shortcut: divide 72 by the annual interest rate to estimate how many years it takes to double your money. For example, at 8%, money doubles in about 9 years.
How accurate is it?
The Rule of 72 is most accurate for rates between 6% and 10%. For rates outside this range, the exact formula (ln(2) / ln(1+r)) gives better results, which this calculator also shows.