You may have noticed that hotels often link two twin beds together to form a single king size bed. The hotel can rent the room to clients who prefer twin beds as well as to others who prefer a king bed. You may have also seen king beds in furniture showrooms featuring twin box springs supporting one large mattress. In the U.S. and abroad, however, both king and twin mattresses come in various dimensions. Not all twin beds combine easily to form a single king mattress.
U.S. Standard Twin and King Beds
Standard twin bed mattresses in the United States measure 39 inches wide by 75 inches long. Standard king beds measure 76 by 80 inches. Exact measurements may vary with a particular manufacturer or model. If you push two standard twin beds together, you get a combined area 78 inches wide and 75 inches long. This is 2 inches wider and 5 inches shorter than a standard king bed.
U.S. Twin Extra-Long and Standard King
A twin extra long bed measures 39 inches wide by 80 inches long. Combining two of these, you get a sleep surface 78 inches wide and 80 inches long. The result still measures 2 inches wider than the standard king, but it has the same length. You can also purchase a pad or bridge to even out the crack between the two mattresses. A king sized flat sheet tucked in or a fitted bottom sheet with sufficient give can cover both mattresses and give the appearance of one bed.
A California king bed is narrower and longer than a standard king. It measures 72 inches wide by 84 inches long. Two twin extra-long beds pushed together, measuring 78 inches wide by 80 long, are 6 inches wider than a Cal king and 4 inches shorter. Two regular twin beds have the same difference in width and measure 9 inches shorter. Neither regular nor extra-long twin beds make a close substitute for a California king.
Sizes in Other Countries
Bed sizes in Canada are similar to those in the U.S., but many other countries have different sizes. In Australia, a single bed measures 36 inches wide by 74 inches long, and a single extra long measures 36 by 80. Two Australian single extra-long beds pushed together have the same size as an Australian king, 72 inches wide by 80 inches long. In the United Kingdom, a single bed measures 35 inches wide by 75 inches long. Two pushed together equal 70 by 75. This size doesn't exactly match either a U.K. king, at 60 by 78, or a super king, at 72 by 78.