All materials are advertised at 12x19 inches. There is some variation though due to the manufacturing and cutting process that can result in pieces being narrower in some cases. We will not send out boards less than 11.75 inches, but in particular Cracked Crystal and some other patter acrylics have special molds that are used to create the pattern. There is also some trimming of edges to avoid inconsistent patterns. This sometimes results in pieces being as narrow as 11.75 inches. If your project requires the full 12 inches, please make the order then email us at firstname.lastname@example.org and we will specifically pick acrylics that meet your requirements. If you ever receive an acrylic that does not meet you needs, contact us and we will correct the problem. Thank you for understanding the variation.