Twin XL, twin extra long or x-long twin sheets all refer to fitted, elasticized sheets sized 39 by 80 inches which fit over and tuck under the mattress. This is five inches longer than a standard twin fitted sheet which measures 39 by 75 inches. A twin flat sheet, which drapes over the sleeper, is standard sized at 66 by 96 inches which may still be sufficient in length for use on an XL twin mattress.
All new sheets will shrink a bit when washed, but the shrinkage is normally mostly in the length. Flannel sheets shrink a bit more, but are cut longer to allow for this. When purchasing flannel sheets, it is sometimes advisable to purchase an XL size even when using a normal sized Twin mattress to assure sufficient overhang for tucking in after the shrinking, according to Cheryl Mendelsen, author of the book Home Comforts: The Art and Science of Keeping House.
Twin XL flannel sheets are sold by on-line on websites such as LLBean.com, Garnet Hill, JC Penney and Bed Bath & Beyond. Check the Resources section below for links.
Twin XL Flannel sheets are sold in stores such as JC Penney and Bed Bath & Beyond. If purchasing sheets for a college dorm room, call the campus bookstore to see if they carry college logo or color themed sheets.
Due to their heavier weight, flannel sheets are considered a winter weight fabric by retailers and sold during fall and winter months as a seasonal item. The twin XL size is not manufactured routinely by some linen makers because it is not a standard size for twin bed home furniture manufacturers. For this reason, twin XL sheets can be harder to find than other materials and sizes. Twin XL sheets are more readily available to purchase online.