The rule of 72 is a process for quickly projecting how long it will take for a rate of investment return to make capital double. The number 72 is used in figuring out the answer by dividing the rate ...

The Rule of 72 formula provides a reasonably accurate, but approximate, timeline—reflecting the fact that it’s a simplification of a more complex logarithmic equation.

The Rule of 72 is a math formula that estimates how long it takes something to double or decline in value and illustrates how compounding interest works. Home Notifications Newsletters Next Share.