Thread count, also called threadcount or threads per inch (TPI) is a measure of the coarseness or fineness of fabric. It is measured by counting the number of threads contained in one square inch of fabric or one square centimetre, including both the length (warp) and width (weft) threads. The thread count is the number of threads counted along two sides (up and across) of the square inch, added together. It is used especially in regard to cotton linens such as bed sheets, and has been known to be used in the classification of towels. There is a common misconception that thread count is an important consideration when purchasing bedding. However, linen experts claim that beyond a thread count of 400, there is no difference in quality. They further highlight that sheet material is of greater importance than thread count. The amount of thread that can fit into a square inch of fabric is limited, suggesting that bedding beyond 400 count is likely a marketing strategy. Inflated thread counts are usually the result of including the number of strands in a twisted yarn in the claimed thread count.