Thread count is a measure of the coarseness or fineness of fabric and refers to the number of threads, both vertical and horizontal, in a one-inch square of fabric. Thread count is affected by a number of factors, including ply (pick) and thickness (cotton count/denier) of the threads used. While fabrics are available with thread counts up to 1000, anything in excess of 400 is considered by many to be a bit extraneous. Using finer threads allows for more thread to fit in a square inch resulting in smoother, softer fabrics, part of the reason these fabrics are considered more desirable than fabrics with a low thread count.
YARN PLY / PICK
This refers to how many yarns are wrapped together into a single thread. Single-pick fabrics use threads on their own, while double-pick fabrics twist two pieces together into a stronger thread, as well as doubling the thread count of the fabric.
This is a measure of linear density. In the United States a cotton count between one and 20 are referred to as coarse counts. A regular single knit t-shirt can be between 20 and 40 count, top of bed products are usually 30-45 count while fine bed sheets are typically 40-80 count. The number is now widely used in the staple fiber industry.
This is a measurement that is used to identify the fiber thickness of individual threads or filaments used in the creation of cloth. This unit of thickness is primarily used for synthetic fibers such as polyester and nylon. Denier counts help to ensure that the fabric durability is in proper proportions for the type of material that is to be produced with the raw fiber. A higher denier count will produce thicker materials and a texture that may not be appropriate for an accessory that is expected to be soft and silky. As an example, pantyhose are about 15 denier while traditional nylon luggage is between 600 and 1,200 denier. Microfiber fabrics used in bedding are between 75 and 150 denier.