The Rule of 72

The Rule of 72 is a simple accounting tool for quickly determining how long it takes money to double at a particular rate of return. To use this tool, simply divide any rate of return into 72. The answer is about how long it takes money to double at that rate of return. For instance, at 6% (72 divided by 6 equals 12) money doubles about every twelve years; however, at 12% (72 divided by 12 equals 6) it takes only six years.