If you enjoy math and want to dig deeper into investment performance, you can also modify the Rule of 72.
One of the most common variations is to simply reverse the equation.
72 ÷ Desired Years to Double Investment = Annual Interest Rate Needed
This modified version of the equation is good if you have a long term savings goal. For example, if you’re saving for a down payment of a house, saving for your children’s college tuition, or saving for retirement, this equation can show you what interest rate you’ll need to reach your goals.
Below is a table showing the Rule of 72 in reverse.