A double size bed, commonly referred to as full size, measures 54 inches wide by 75 inches long. The height varies from as little as 4 inches to over 17 inches, depending on manufacturer and construction.
The double, or full size mattress was common for couples in the early half of the 1900s, due to the smaller size of homes and bedrooms. In 1958 Simmons introduced the queen and king size beds, which provided more width and additional length. While the double mattress remains common for smaller homes or singles, as of 2014, the most popular mattress size available is the queen, measuring 60 inches wide by 80 inches long.