The standard full-size bed frame is 54 inches wide and 75 inches long. There may be some variation, particularly in adjustable bed frames that can expand to king- or queen-size or contract to twin-size; 80 inches is a common length for these.
Full-size beds may also be referred to as double or standard size. Standard width varies more than standard length among different bed sizes, with a 34-inch range in width but only a 9-inch range in length.
Twin beds are typically 38 to 39 inches wide, with full beds, the next size up, 15 to 16 inches wider. Both twin and full are normally 75 inches long. King and queen beds are both 80 inches long, but queen is 60 inches wide while king is 76 to 78. Another size variant, the California or Western king, is narrower than both queen and king at 72 inches, but longer than both and all others at 84 inches.