Not everyone agrees that higher thread count make better sheets. There are other factors worth considering. These are yarn size and ply. Yarn size refers to the thickness of the yarns that are used to make the fabric. A higher yarn size means a finer yarn. Generally sheets are made from a yarn size range of 40 to 100. Obviously, the finer the yarn, the more of them will fit in a square inch.

Ply refers to the number of individual yarns used as a strand. Single ply fabric is woven from one, individual yarn; 2-ply fabric is made from yarns that are twisted together and then woven. If 2-ply yarn is used, the finished construction will have twice the thread count of the same construction made from single ply yarn. 400tc Egyptian cotton sheets may be up there in thread count but it should also have a very high yarn size or it will come out bulky, thick and heavy.