I like Francie's answer. QUILTING SHOULD BE FUN !!!!! so don't worry about an exact measurement. I don't use a 1/4 " measurement, I use the edge of the pressure foot. That way I am consistent in the quilt and I square off with my rotary cutter anything that's off. The only time this would be an issue is if you were working on a group project, but wait....not all of their's are 1/4" either.