I first make narrow cut to even up edge of fabric by lining up ruller with line on the mat. After straightneing edge i then position ruler on fabric at distance that I need strip to be and then cut. I agree that mat lines are not accurate enough. I have a large square 20 x20 ruler that I use for cuts bigger that 6". It is really nice for larger strips/blocks. It was still about $25 after 50% off coupon at Joann's but well worth it! i