In bowls there are 2 different mats i.e. there is an indoor mat which the game is played on these can be any size to suit the area available, for competition they must be in excess of 23m.
Then there is the mat on which the bowler stands in crown green the mat is 5.5" dia on which the bowler has to place their leading foot, in flat green the mat is 24"X 12" on which the bowler starts with both feet.