Measure the area for the rug and decide on a rug size. Consider door swings, traffic patterns and furniture placement. Use paper bags or kraft paper and tape to simulate the size of the rug and get a good visual confirmation on the final rug size. Cut, flatten and tape the paper bags together to create a template the size of the proposed rug; roll the kraft paper out and cut to the correct size using tape to connect several pieces together to create a template.
Take a tape measure and the rug measurements and search for the right carpet remnant for the new rug. Visit remnant stores and home remodeling centers. Measure the remnant and purchase one that matches or is larger than the size needed.
Unroll the remnant and lay it face down on the floor. Measure and mark the rug size on the back of the remnant using a tape measure, straight edge and wide tip marking pen. Use a straight, clean cut side of the carpet as one edge of the rug and measure the rug using that edge as a starting point.
Use a carpet or mat knife and cut out the rug. Cut from the back of the carpet. Make sure the surface below the carpet is protected--use flattened cardboard boxes or work directly on a concrete surface that does not require protection.
Flip over the remnant and view the new rug. Trim away any lose fibers with scissors.
Bind the carpet by sending it to a local binder or use an instant carpet binding product to seal the edges. White glue is an an alternative way to protect the backing from fraying and coming apart around the edges. Place the carpet face down and paint a 1-inch border of glue around the edge of the backing. Make sure the actual edge of the backing is coated. Allow to dry overnight.