Twin beds are the most popular for single sleepers, while queen beds are the most popular for double sleepers. A standard twin mattress measures 39 by 75 inches, and a standard queen mattress measures 60 by 80 inches.
Twin beds are popular for children's rooms, multi-use rooms and college dorms. They fit in small spaces but may be too short for a tall adult, who may need an extra-long twin bed measuring 80 inches long. As bed linens rise in price with the size of the mattress they are made to fit, twin beds are the least expensive to buy sheets for.
Queen beds offer enough room to sleep two adults comfortably and fit into smaller spaces than king beds, which measure 76 by 80 inches. Full-sized beds measure 54 by 75 inches and are fine for two children, but may be too cramped for two adults.