What does the rule of 72 help estimate?

The rule of 72 is a useful formula that helps investors estimate how long it will take for an investment to double in value based on a fixed annual rate of return. By dividing 72 by the annual interest rate of the investment, you can quickly calculate the approximate number of years needed for the investment to grow to twice its original amount. This estimation is particularly handy because it simplifies more complex calculations related to compound interest.

For example, if an investment earns 6% annually, dividing 72 by 6 gives you 12, indicating that it would take about 12 years for the investment to double. This rule is widely used in finance because it provides a straightforward way to understand the power of compound growth without needing a calculator.

This tool specifically focuses on investment growth, which distinguishes it from other financial considerations like tax implications or total savings within a year.