Rules of 72 is a simple estimation of how long an investimate will take to double the principal at a fixed compound rate of return. By dividing 72 by annual rate of return, an investor will obtain the time it will take to double the money. At a 5% annual return, it will take 14.4 years to double the initial investment while 10% annual return will take only 7.2 years. The higher rate of return will double your money faster.

You may also use our million dollar calculator to determine how long it will take to save $1M dollar, or use compound interest calculator to calculate your retirement savings.