http://sportsbookmagazine.com/managearticle.asp?c=160&a=311
Simply put, the field must be a clearly delineated rectangle, with the sidelines longer than the length of the goal line. The exact measurements of the field may vary somewhat, however. The fields must be between 100 and 130 yards long (90-120 meters) and between 50 and 100 yards wide (45-90 meters). For full international matches like World Cup Qualifiers, the measurements tend to be a little stricter, with the minimum sizes raised, but the maximum sizes toned down to a degree (generally 110-115 yards long by 75 yards wide).
