I had to cut the pad to size.  I started with a kitchen shears, but it was way too hard on my hands.  I switched to a utility knife and using an old piece of plywood underneath to made the necessary cuts.  It did take multiple passes over the pad with the knife to get through and it did leave fuzzys hanging after the cut, but trimmed them with the kitchen shears. Overall the pad works very nicely under our rug.