Rule of 72 calculator
How many years does it take money to double? Enter a yearly rate to see the rule-of-72 estimate and the exact answer, or pick a number of years to see the rate you'd need. Free, no sign-up, nothing leaves your browser.
The exact figures assume growth is added once a year. This is a calculator, not advice: returns on investments are not guaranteed.
What the rule of 72 is
The rule of 72 is a quick way to estimate how long it takes money to double with compound growth: divide 72 by the yearly percentage rate. At 6% a year, money doubles in about 72 ÷ 6 = 12 years. It works the other way too: to double in 8 years you need about 72 ÷ 8 = 9% a year.
Inflation works the same way
The rule also shows how fast prices double, or how fast cash loses half its buying power. At 3% inflation, prices double in about 24 years. The shortcut is closest for rates between about 6% and 10%; the exact figure is shown next to it.
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