Well! I measured my mat and at first inspection everything seemed okay, if I looked at the distance between any two parallel lines, it appeared to be an inch. But it must have been off a teeny, tiny fraction because when I checked at the end of my ruler the lines no longer matched up! The tiny bit eventually added up to something discernible! I see I will have to change everything about how I cut stuff out, including the direction that I place the yet-to-be-cut fabric and will need to invest in a ruler larger than the 3 x 18 that I currently have. Thanks for the heads-up, Tiffany!!