A traditional queen-sized bed is 60 inches wide by 80 inches long and a traditional twin size bed is 39 inches wide by 75 inches long. Some manufacturers have slightly changed the overall dimensions of the mattress sizes that they offer, so specific manufacturer sizing should be checked before purchasing.
Due to their smaller size, twin mattresses will generally fit comfortably in tight rooms. Twin beds are also one of the easiest beds to make and the least expensive to purchase linens for. The queen bed, if shared, provides less sleeping space per person than a twin. Two twins together is the same width as that of a king-sized bed.