What is Thread Count and why does it matter?

Thread count 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 and thickness of the threads used. The ply of the fabric refers to how many threads are wrapped together into a single thread. Single-ply fabrics use threads on their own, while two-ply fabrics twist two pieces together into a stronger thread, as well as doubling the thread count of the fabric.

Using finer threads also allows for more thread to fit in a square inch. Finer thread often results in smoother, softer fabrics, part of the reason high thread count fabrics are considered more desirable than fabrics with a low thread count. Finer thread also results in a more fragile fabric, however, which may not always be ideal. Two-ply fabrics help solve this problem somewhat by strengthening the threads and creating a more durable, though heavier, fabric.

The general wisdom is that a thread count of higher than 100 is desirable --these fabrics are known as percale -- with somewhere above 180 being ideal. While fabrics are available with thread counts up to 1000, anything in excess of 400 is considered by most to be simply extraneous. In the case of some fabrics, a high thread count is simply not a viable option. Flannel, for example, as a result of its other properties as a material, has consistently low thread counts, but this is in part what gives it its sought-after feel.