Generally speaking, the standard sizes for fabric cutting mats are 18″ x 24″ and 24″ x 36″. An 18″ x 24″ mat gives you a reasonable amount of space to cut most fabrics easily. However, if you work on larger quilts or home dec projects frequently, the 24″ x 36″ mat provides notably more room to maneuver. No matter what size you choose, be sure it’s big enough for your needs.