Standard sleeping pads are 72 inches long and 20 inches wide. Long pads are 78 inches. If you are backpacking and weight is a concern, then select a short pad that is three-fourths the length of a normal product. Double-wide sleeping pads are 40 inches and work a lot better than piecing two sleeping pads together. (Note: If one person is a hot sleeper, and the other is a cold sleeper, you might be better off with two separate sleeping pads.)   You’ll also want to consider which sleeping pad shape will work the best for you. Brandon Bowers, Product Manager at Therm-a-Rest, says, "When you choose a sleeping pad, there are a few considerations to make, like the pad shape and size. We have rectangle and mummy pads. The mummy pads shave a little weight and are smaller in size, therefore more packable for backpacking. The pad size should also be based on your height. In terms of width, most of our mattresses are 20 inches wide, but we also offer wide pads that are 25 and 30 inches wide for increased sleep area.”