Typically, sheets with thread counts of 200 to 800 are the best purchase. Thread count is the amount of yarn per square inch. It does not, however, determine the sheet's quality. Use caution because some high thread counts are achieved by low-quality construction.
Several factors decide if sheets are high quality, including fiber, finishing, weave and the location where the thread was manufactured. Long fibers, such as Egyptian cotton, organic cotton and cotton-poplin, create a stronger structure.
Avoid sheets that have shrinkage control. These sheets are often finished with harsh chemicals. Some countries, such as France and Italy, tend to produce higher quality sheets.