Rule of 72 Calculator
How many years it takes to double (and triple) money at a given return.
Result
Years to double
9.0
Years to triple
14.3
How it works
Years to double = 72 ÷ rate
The rule of 72 is a quick mental shortcut: divide 72 by the yearly return to estimate the years needed to double your money. 114 estimates tripling.
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Frequently asked questions
How accurate is the rule of 72?
Very close for rates between about 4% and 12%; outside that range it drifts a little.
Why 72?
72 has many divisors and matches the compound-interest math closely for typical rates.
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