When I started quilting (years+ ago) and took a 101 class at my LQS, the instructor had us turn our mats over (no lines, on the green ones). So that we would learn to us only our rulers for measuring. IMHO that was a great learning lesson.

I've taught my classes for years that they should use rulers for measuring and mat line for cutting....in fact I make them turn their (Olfa) mats over to use where there are no lines! We also use only Omnigrid (the yellow lines of which I personally don't care for) or Olfa rulers, too.

Jan in VA

Like a lot of other posters I use my mat to line up my fabric, but my ruler to measure and cut,

I only used the mat for straightening the edge. I also try and use the same brand of ruler for an entire project.

I will echo what others have said....I never depend on the mat for measurement, only for lining up straight edges. I also try to use the same brand of rulers. I have been told they vary by brand.

I know everyone says not to use the mat for measuring but when you are doing something wider than your ruler what are you supposed to do? I use Olfa mats and Olfa rulers and I've checked them for accuracy and they match.

Joyce , if you are cutting a wide strip, use two rulers next to each other in the same manner as a narrow strip.

I use to take all the workshops and classes I could when I started quilting. I learned so much and how to do something the right way before taking shortcuts. Now we have Craftsy classes!

I use my ruler to cut to measure. I don't use the mat to measure. I do line the ruler with the mat but measure everything with my rulers. I also measure my rulers against each other. I like my June tailor and have had no problems with it. Been 4 years just make them aware that their mats are not true measure.