Most American mahjong mats are square. Measure the table first, then leave room for racks on all four sides.
Common sizes
31 to 33 inches suits many standard card tables. 36 inches needs a larger dining or folding table. If racks hang off the edge, go smaller, or use a table that is at least 8 inches wider than the mat on each side so racks and pushers sit flat.
Surface
A padded or neoprene face keeps tiles from sliding and lowers noise — helpful for evening games. A non-slip rubber back keeps the mat from walking during the Charleston. If your table is glossy, prioritize the non-slip back over extra padding.
Marked vs plain
Some mats print wind positions or Charleston direction guides. These help new players; experienced groups often prefer a plain design that matches the room. Both work — pick based on who plays most often.
Care
Roll (don't fold) the mat for storage, and spot-clean with a damp cloth. Keep it out of direct sun so colors don't fade.
Shop sizes on mahjong mats. Pair a new mat with featured tiles and racks for a complete table.