Crib/Toddler 28" x 52"
Twin 39" x 76" Smallest adult bed mattress
Twin X-Long 39" x 80" Commonly used in college dorm rooms, ­longer than a standard Twin but the same width
Full/Double 54" x 75" Shorter and narrower than a Queen
Queen 60" x 80" Wider and longer than a Full/Double
King 78" x 80" Largest mattress
Cal-King 72" x 84" Narrower and longer than a King