Rule of 72

How long does it take to double your money? It depends on the growth rate. The Rule of 72 is a simple math formula to determine the number of years it would take for a sum of money to double. Simply divide an assumed rate of growth (let’s say 7%) into 72. The answer: 10 years. If the rate of growth was 10% the answer would be 7 years.
The example below shows a current balance of $3,125 doubling every ten years. The most important aspect of this chart to notice is that fully half of the ending balance of $100,000 was created in the last ten years of the 50-year time period shown. You can see how critical it is start saving early.