The Rule of 72

Use the calculator on this screen to estimate the amount of time or interest rate you’d need to double your money on savings or an investment.


Let’s say you have an investment that’s earning 8% per year. Start with the number 72 and divide it by the interest rate, eight. 72 divided by 8 equals 9. This means it would take about nine years for your original investment to double. Try another example for yourself.
If you type in an interest rate and you’ll see how many years it will take your original savings or investment amount to double. Or if you want, type in the number of years, and you’ll see how high the interest rate would need to be.
We hope the Rule of 72 inspires you to get the highest return you can on your savings and investments! Click the Next button to continue.
What is investing? Saving vs. investing Types of investments Types of investments … continued Inflation erodes purchasing power Compounding grows money The Rule of 72