How long would it take you to double your money through savings and investments? It’s easy to figure it out using a handy formula called the Rule of 72. If you divide 72 by the interest rate you earn, the answer is the number of years it will take for your initial savings amount to double in value.

For example, if you earn an average annual return of 1% on a bank savings account, dividing 1 into 72 tells you that your money will double in 72 years. But if you earn 6% on an investment, your money will take only 12 (72 ÷ 6 = 12) years to double.

You can also estimate the interest rate you’d need to earn to double your money within a set number of years by dividing 72 by the number of years. For instance, if you put $500 in an account that you want to grow to $1,000 in 12 years, you’ll need an interest rate of 6% (72 ÷ 12 = 6).