All standard-size rubber bands are assigned a number from 8 to 117B, and each number equates to a measurement. For example, Number 8 rubber bands are the smallest on the list and measure 7/8 inch long and 1/16 inch wide. Number 107 rubber bands are the largest on the list and measure 7 inches long and 5/8 inch wide. Of course, there's no need to memorize the number of every size of rubber band. If you find a particular size useful, however, knowing it's number will make it easier to find and order it the next time.