100 yards is the length of an American Football field. As there are three feet to a yard, and 12 inches in a foot, we have 3 x 100 x 12 = 3,600 inches along that length. There are exactly 25.4 mm in an inch, therefore, we have 3,600 x 25.4 = 91,440 mm, or a short 91.44 m to run from end zone to end zone.