The Rule of 72

The Rule of 72 is a quick way to estimate how long it will take for an investment to double in value based on its annual interest rate. To use it, divide 72 by the annual interest rate (expressed as a percentage). For example, at 6% interest, it takes about 12 years (72 ÷ 6) for your investment to double. It’s a useful mental shortcut for understanding the power of compound growth, though it provides an approximation rather than an exact figure.