Measure the dimensions of the room where you would like to use an area rug. Transfer these dimensions to 1/4-inch graph paper using a straight edge and a pencil. Note the location of doors, door swings, windows, floor vents, ceiling light fixtures and any room feature that should be considered in rug placement.
Determine the size of the area rug by using a few guidelines. In a dining room, the rug should be large enough so that when people sitting at the table pull their chairs back, the chairs will still be on the rug. In a living room, the rug should tuck under the front legs of the sofa and chairs. In a bedroom, the rug should be large enough to extend beyond the sides of the bed by at least 3 feet on each side.
Measure for a large area rug by measuring the full size of the room. Identify and measure any furniture that is positioned against the wall. Most furniture that is positioned against walls is less than 2 feet deep. You will want that furniture to rest on the existing floor, so reduce the size of the area rug by more than 2 feet on each side for an even appearance.
Turn the carpet face down on a clean concrete surface that cannot be damaged by carpet knives. Measure and mark your finished dimensions on the back side of the carpet. Use a long piece of straight scrap lumber as a straight edge so you have cut lines.
Cut the carpet with a carpet knife and carpet shears, being careful to cut completely through the carpet and any carpet backing.
Paint the raw edge of the carpet with white glue using a 1-inch disposable paint brush. This will reduce fraying. Allow the glue to dry completely.
Finish the edges completely by applying a color coordinated binding tape around the entire perimeter of the rug. Use a hot glue gun to glue the edge carpet fibers to the binding tape. (It is not necessary to paint the edge with white glue if you are installing a binding tape.)