The number of squares on the square side is 15 x 16. Hexes are 17/16 x 16. The width alternates between 17 and 16 hexes, so no play space is wasted.

Please note: Never use dry erase, permanent, or grease-pencil markers. The vinyl is too porous for the lines created from them to be able to be removed. Use water-soluble markers/pens. If you have any doubt of the suitability of any particular marker, draw a small line on the border, let sit for a while, and see how well it can be removed. Better to have a small permanent blemish on the edge of the mat than a permanent map drawn on the entirety of the mat.