The rule states that the amount of time required to double your money can be estimated by dividing 72 by your rate of return. For example: If you invest money at a 10% return, you will double your money every 7.2 years. If you invest at a 7% return, you will double your money every 10.2 years. What interest rate will double money in 10 years? To use the Rule of 72 in order to determine the approximate length of time it will take for your money to double, simply divide 72 by the annual interest rate. For example, if the interest rate earned is 6%, it will take 12 years (72 divided by 6) for your money to double. How can I double my money in 5 years? This is the number of years it will take for your money to double. For example, if your money is earning an 8 percent interest rate, you’ll double your money in 9 years (72 divided by 8 equals 9). Or, if your money is earning a 5 percent interest rate, you’ll double it in 14.4 years (72 divided by 5 equals 14.4). How can I double my money? If you divide your expected annual rate of return into 72, you can find out how many years it will take you to double your money. Let’s say, for example, that you expect to get returns of 10 percent a year. Divide 10 into 72, and you discover the number of years it takes you to double your money, which is seven years. How long does it take to double your money in the stock market? At 12%, you could double your initial investment every six years (72 divided by 12). In a less-risky investment such as bonds, which Standard and Poor’s says have averaged about 6% over the same time period, you could expect to double your money in about 12 years (72 divided by 6).