The Rule of 72 Explained

The Rule of 72 is a mental math shortcut to estimate how long your money takes to double at a given interest rate. Divide 72 by the annual return.

Example: 8% return ? 72/8 = 9 years to double. 6% ? 12 years. 10% ? 7.2 years. For inflation, use 72 to see how quickly purchasing power halves: 3% inflation ? 24 years to halve.

It's an approximation (accurate from 6�10%), but powerful for quick comparisons. It shows why high fees (2%) devastate returns: 7% vs. 5% return means 10 vs. 14 years to double � a huge difference over a 30-year career.

Keep this tool in your mental wallet. It will serve you well in investing, debt, and inflation decisions.