The width of the board is 20" and the length is about 6" longer than your ironing board. I used 3/4 " plywood because that's what we happened to have on hand , but you could use 1/2" or 5/8" The little blocks which were glued and screwed in place were 6" long. The 3/4 " plywood makes it fairly heavy to lift off but for the number of times I actually iron it's not a problem.