Rule+of+72

To double your money in a savings account, the rule of 72 shows in how long it will take for your money to double at a given interest rate.

The rule says that to find the number of years required to double your money at a given interest rate, you just divide the interest rate into 72. For example, if you want to know how long it will take to double your money at 4%, then divide 4 into 72 (72/4) and you get 18.


 * For instance, if you were to invest $100 with compounding interest at a rate of 9% per annum, the rule of 72 gives 72/9 = 8 years required for the investment to be worth $200; an exact calculation gives 8.0432 years.

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