Thread count in sheets is the number of horizontal and vertical threads or yarns per square inch. A higher thread count is supposed to indicate higher quality, but that isn't always the case. There are other measures of bedding quality that contribute to your comfort and justify your investment in good sheets. Understand the terms and tricks of the bed linen market to get your money's worth and get your Z's.
Anything over a 200 thread count is acceptable, and aiming for 200 to 400 thread count will maximize your value for cost. Beware of claims that exceed an 800 count. Manufacturers boast as high as 1,200 thread count, but looms typically don't have room for that many threads. An abnormally high thread count could indicate "stuffing" the loom with thinner threads to boost the numbers. That practice actually lowers quality.
Figure out your objective before you start counting threads. Not all sheets are woven alike and specific weaves yield different results. A basic weave -- you won't see a label for this style -- has an equal number of vertical and horizontal threads and a plain weave. Percale is woven in a basketweave pattern, has a thread count of at least 180, is durable and has a crisp feel. Sateen sheets have more vertical than horizontal threads, a configuration that makes them very soft but tends to result in pilling and may shorten the life of the sheet. Fancy weaves mix higher quality with higher prices.
The length of the cotton fiber is a primary consideration when hunting for high-quality sheets. Egyptian, pima and Supima are extra-long-staple cottons -- ELS. Extra-long-staple means the fibers are very long; they spin into a sturdy yarn; they are very soft; and they resist pilling. Sheets made from superior ELS cottons with long fibers are trademarked and cost more. But they last longer and are more comfortable than ordinary-length fibers, too. Always look for the licensed trademark or the black-and-white Egyptian Cotton government label to be sure you are buying genuine, 100 percent, long-staple cotton sheets.