Investing And The Rule OF 72

If you want to quickly figure out how long it would take to double your money, use the rule of 72.

72 divided by interest rate = number of years to double your money.
  • If you receive a 6% interest rate, divide 72 by 6, which gives you 12.  This means it will take you 12 years to double your money.  The reverse: If you know you want to double your money in eight years, divide 8 into 72 to find that it will need to find a 9% interest rate to achieve that.