I got to thinking when I was cutting some blocks and lining them up with my line on the mat.
Do you put the ruler on the line making sure the fabric is lined up with that line or do you put your ruler so the line of your ruler is hitting the fabric?

I don't use the lines on my cutting mat...I use the lines on my ruler. I square up my material first before I begin cutting...I do that using the 2 ruler process.

I use the line on my ruler- the 2nd thing you said!

I never use the lines on my mat. I don't think they are accurate enough. If necessary I use 2 rulers, but never the mat.
Sue

I put the ruler so the edge is just a hair on the left side of the line on the mat. That way the cut is exactly on the line on the mat.

whether you use the ruler or the mat, just make sure you use the same throughout the whole cutting process of the same project. i bought a new mat recently by fiskars and the lines are quite thin. it is the best mat i've ever had. love it.

Same here

Ditto!!!!! me too!

I cut with the ruler lines, never the mat lines....and I try to make sure the line on my ruler is sitting on the fabric...just on the edge...and to be consistent with that...

I don't think the mat lines are accurate enough. I use the ruler lines.