Whether you're shopping for bed sheets or sewing your own, you'll find there are four common mattress sizes: twin, full, queen and king. However, that doesn't mean there are only four sizes for the accompanying bed sheets. You must know the depth of the mattress as well as the width and length dimensions. Some mattress models are thin, while others are quite thick. The bottom fitted sheets are available in a variety of sizes to accommodate these different mattresses, but the top flat sheet sizes remain more consistent for each of the four common mattresses.
Twin and Twin Extra Long
There are two varieties of twin mattress beds, each with different measurements and each designed for one person to sleep on. The most common is the standard twin, which many people have as youths and well into their teenage years. The industry standard twin mattress is 39 inches wide by 75 inches long, and the average twin flat sheet is 66 by 96 inches. The second version of the twin mattress is commonly known as the twin extra long, or student twin. This size is popular for older teens and in college dormitories, with an industry standard mattress size of 39 by 80 inches and an average flat sheet size of 66 by 102 inches.
Full or Double Size
A full size mattress, also known as a double mattress, is a step up from the twin. This size mattress can sleep one or two people, but many couples might find it a little smaller than desired. The industry standard double/full mattress is 54 inches wide by 75 inches long. The average flat sheet size for this bed is 81 inches wide by 96 inches long. Being the same length as the standard twin mattress, some adults may find the full size mattress too short for their comfort.
Queen size mattress beds are designed for one or two people and allow ample room for most couples to sleep comfortably. The industry standard queen mattress is 60 inches wide by 80 inches long. Queen size flat bed sheets are 90 inches wide by 102 inches long, on average. The extra inches on both width and length have made this the most popular mattress available.
King and California King
The largest common mattress sizes are the king and California king. The industry standard king size mattress is 76 inches wide by 80 inches long, with an average flat sheet size of 108 by 102 inches. The California king is slightly narrower and longer, with an industry standard mattress size of 72 inches wide by 84 inches long. The average flat sheet size for a California king is 102 inches wide by 110 inches long.