BKrenning

After googling what size your existing rulers are--6.5 x 12" & 6.5 x 24", I now understand your problem. You can do it with those rulers but it is going to be much easier to get yourself a nice big square ruler. I would suggest 12.5" or 15" square.

The easiest way to use your existing rulers would be to mark your line at say 2" and then measure from that line so square off an edge of the fabric--use the big daddy ruler (if you're doing a single fold, width of fabric) and measure and mark 2". Oh, and I would turn the fabric wrong side out & mark very lightly with pencil. Now take the big daddy ruler again and lay it so that you have 4 7/8" of fabric to the right side of the line you just drew if you're right handed. In other words, you're going to lay the ruler down on the line you drew and measure 4 7/8" from that line. You'll end up with a strip that is 6 7/8" wide which you can easily sub cut into squares.

If you're left handed--you're going to do it from right to left instead.

I would use a mechanical pencil with a very fine lead.

I just remembered that they make little gizmos that let you stick 2 rulers together. I don't remember what they are called and I still think you'll be better off using a large square ruler.