What Are Fine Linens & High Thread Count Sheets?
So what exactly are high thread count sheets? Thread count is simply a measure of how many threads—warp (lengthwise) and weft (widthwise)—are woven into one square inch of fabric. The thread count of "standard" cotton or muslin is around 150; good-quality sheets start at 180-thread count; and a count of 200 and higher is considered percale.

Thread count also has to do with the yarn construction and quality of the yarn. With finer threads, like those produced with Egyptian cotton, more can be woven into each square inch, producing a finer fabric.

As a practical issue, just how many threads can fit into one square inch of fabric? While improvements in spinning and milling technologies have pushed up the numbers, thread counts above about 400 are something of a misnomer, generally entailing the use of a "plied" yarn—one that is produced by twisting together gossamer-fine threads. For marketing purposes it is not uncommon to count the twisted yarn as double and, for example, describe fabric with 250 individual four-ply yarns in a square inch as a 1,000-thread-count product. But according to accepted textile industry practices, while they may make incredibly soft and luxurious sheets, plied yarns do not multiply thread counts.

Fine linens begin with fine cotton, and the quality of the cotton depends on the lengths of the individual fibers, or staples—the longer the staple, the better the cotton. Longer staples can be combed finer to remove more small fibers, allowing the cotton to be spun into a finer-textured thread with more tensile strength, and woven into a softer, more lustrous fabric.

Egyptian cotton is acknowledged as the best quality, longest-staple cotton in the world. Although historically it all came from Egypt, today "Egyptian" cotton is also produced in other countries. It still complies with the original Egyptian standards of quality, including a 1- to 2-inch staple, compared, for example, with Pima cotton’s 1-7/16 inch staple.