You can butt two rulers up against each other. Say, you need a 16&1/2" square to cut in quarters for setting triangles. Use the 12&1/2" ruler combined with (butted up against) a 6" ruler. With the even edge of the fabric to your left, lay the 6" ruler so that 2" is to the left of the cut edge and 4" is to the right (as if you were going to cut a 4" strip) then butt the 12&1/2" ruler up against the 6" ruler. So now you have 4" + 12&1/2" or 16&1/2". Make your cut against the right hand side of the bigger ruler. Is this clear as mud? utt

I do use the lines on the mat all the time.

I just use the bottom line to make sure the fabric is even, and i use the side lines to gauge how straight i am holding the ruler

I use the two rulers, also, and love to just use my ruler to line up the fabric for a cut.

I use the mat lines when I true up a fabric, but rely only on the lines of my rulers when actually cutting.

This is how I was shown to cut fabric too - now I'm looking to buy a little bit larger cutting mat. So yes, I use my mat all the time for cutting with the rotary cutter.

I always do it that way, lining up the ruler with the mat. It is the easiest way for me.

i use the mat but if i do that i dont combine it with any other way of measuring, either mat or ruler all the way never both i heard the two could be differant

Before I read the other posts I will put in my 2 cents :lol:
Only when I don't have a large enough ruler, not very oftern and not if I don't have to.

I do on rare occasions. I was told mats aren't always true