Fleece, also called polar fleece, is used for blankets because it is an extremely warm fabric that wicks moisture away. The biggest challenges, when cutting fleece to make a blanket, are due to the thickness of the fabric. Cutting straight lines and getting a smooth edge requires practice, but fleece is a forgiving fabric, and using the right sewing supplies reduces the practice time required. Fleece's raw edges do not fray thanks to the manufacturing process used, but jagged edges form when care is not taken cutting the fabric.
Determine the size you want for your fleece blanket. A baby blanket can be as small as 1 square yard, but fleece blankets can be as large as needed.
Spread the fleece out on the work table, and place the yardstick on the fabric along the selvedge edge. Make a small mark on the fleece, at the end of the yardstick, with the tailor's chalk. You do not need to draw the whole line.
Mark the fleece at the other end of the yardstick when you reach the desired length. Measure across the raw edge, marking the fleece at the end of the yardstick when you reach the desired width. Mark out the other two ends after measuring, keeping the shape squared.
Inspect the shape to make sure the marks are straight, and line the yardstick up against the left side of the marks. Hold down on the yardstick with a firm pressure so it does not move. Place fabric weights on each side of the fleece, 1 foot from the end closest to your body.
Hold the rotary cutter in your right hand, release the safety button, and place the blade against the right edge of the yardstick 1 inch in from the end. Hold the cutter at a 45 degree angle, and press down firmly, cutting through the fleece. Roll the cutter slowly back toward your body.
Roll the cutter forward, staying along the yardstick's edge until you reach the end, without lifting the cutter out of the fabric until you are done. Repeat on each edge.
Tipping the rotary cutter will cause your straight line to curve slightly, so hold the cutter vertical to the fabric. Lifting the cutter out of the fabric will cause jagged edges, so it is important to make the cut in a long, smooth motion. You can cut the fleece without marking the corners if desired, but if you are new to cutting fleece with a rotary cutter, it is best to mark the corners.