Here is a how to video made by me about tearing a straight edge instead of cutting it. Video length is 1:14
Another tip I forgot to mention in the video
- Always begin by tearing your raw edge first (Raw edge is also called a salvage). This is because the person at the cutting counter probably didn't cut a perfect edge along the grain of the fabric, and after washing your fabric it will unravel unevenly along the raw edges. So to make sure that your dimensions are correct, always begin by squaring up the side.