Bed Dimension Reference Calculator

The six mattress footprints in common use across the United States are nominal trade sizes rather than legal standards: Twin at 38 by 75 inches, Twin XL at 38 by 80, Full or Double at 54 by 75, Queen at 60 by 80, King or Eastern King at 76 by 80, and California King at 72 by 84. Finished mattresses routinely vary by half an inch to a full inch from these figures because quilting, edge encasement and cover stretch differ between makers. The most useful derived number is width per sleeper: a Full gives two adults only 27 inches each, narrower than the 28-inch width of a standard crib, while a Queen gives 30 inches and a King gives 38 inches, the same shoulder room as a Twin. Fit in a room is a clearance problem, not an area problem. Designers generally want at least 24 inches of walkway on each side that is actually used, 36 inches at the foot for passage and for making the bed, and 30 to 32 inches of swing clearance for any door opening into the space. Nightstands are added to the bed width before the walkway is checked, so two 24-inch tables turn a 60-inch Queen into a 108-inch wall run. The main caveats are that frames add roughly 2 to 6 inches per side and sleigh or upholstered designs can add a foot of length, and that mattress height, typically 10 to 14 inches, changes both sheet pocket depth and the ease of getting in and out.

Standardized bed sizes are a product of the industrial mattress trade rather than of any standards body. Through the nineteenth century bedsteads were built by joiners to the dimensions of the room and stuffed ticks were made to fit them, so sizes were local. American manufacturers began converting to innerspring mattresses in the 1920s and 1930s, and because coil units had to be produced on fixed tooling, a small set of repeatable widths hardened into the trade names Twin and Double. The bedding manufacturers association formed in 1915 gave the industry a forum in which those nominal dimensions and the matching bedding sizes could be shared. Queen and King entered the catalogues in the late 1950s, driven by rising average heights, larger postwar suburban bedrooms and a marketing push toward a wider shared bed. The California King, longer and narrower than the Eastern King, is generally traced to Los Angeles bedding makers of the same period who built extra-long beds for custom orders. Twin XL, at 80 inches, spread through American college dormitories because it fits a growing adult in a narrow shared room, and two of them side by side reproduce a King exactly, which is why split-King adjustable bases use them. Outside the United States the metric convention settled instead on a 190 or 200 cm length with 90, 140, 160 and 180 cm widths, so no European size is an exact match for an American one.