When opened up, a queen-sized sleeper sofa measures approximately 84 inches wide and 90 inches long. When it's opened up to a bed, two people can sleep comfortably, and as a sofa, it comfortably seats three people.
A full-sized sleeper is a little bit smaller, with a width measurement of 72 inches and a length of 90 inches. When used as a couch, its size falls somewhere between a regular couch and a love seat. Twin-sized sleepers are the smallest and are sometimes referred to as chair and a half beds or chair beds. They are less than 6 feet wide and sleep one person.