Thread Count & Cover Factor Calculator
Combine ends and picks per inch into a thread count and warp:weft balance, and — when you know the yarn counts — the Peirce cover factor that tells you how tightly the cloth is actually woven.
Thread count & cover
Add both warp and weft yarn counts (Ne) to see Peirce cover factors.
Beyond the marketing number
Thread count is a useful shorthand, but it only counts threads — it says nothing about how thick they are or how much of the surface they cover. Two fabrics with the same count can feel completely different. The warp:weft balance hints at the construction (a plain balanced weave versus a warp-faced twill), while the cover factor puts a real number on tightness by weighing thread spacing against yarn fineness.
That is why premium sheeting is better judged by fibre, yarn count, and cover than by a headline thread count alone. Enter the yarn counts and you can compare a genuine 200-count percale against an inflated 600-count on equal terms.
Frequently Asked Questions
How is thread count calculated?
Thread count is the number of threads in one square inch of woven fabric: the ends per inch (EPI, the lengthwise warp) plus the picks per inch (PPI, the crosswise weft). A sheet with 100 EPI and 80 PPI has a thread count of 180.
What are ends and picks?
Ends are the warp yarns that run the length of the fabric on the loom; picks are the weft yarns that cross them. Counting how many of each fall in an inch — often with a linen tester or pick glass — gives EPI and PPI, the two numbers behind thread count.
Is a higher thread count always better?
Not necessarily. Above roughly 400, extra thread count is often reached by plying thin yarns or by marketing maths rather than a genuinely finer weave. Fibre quality, yarn fineness, and finish affect the hand of a fabric at least as much as the raw count.
What is cover factor?
Cover factor describes how much of a fabric's area is covered by yarn — in effect, how tightly it is woven. In Peirce's cotton system the warp cover is EPI ÷ √(warp Ne) and the weft cover is PPI ÷ √(weft Ne). The cloth cover factor combines them as K1 + K2 − (K1·K2)/28.
Why do I need yarn counts for cover factor?
Thread count alone can't tell you how tight a fabric is, because the same number of thick or thin yarns cover very different amounts of area. Cover factor brings in the yarn count (Ne) so that thread spacing is judged against yarn thickness — which is why the tool asks for warp and weft counts to compute it.
Educational reference only. Cover factor uses the Peirce cotton-system approximation; woven-fabric tightness also depends on weave, crimp, and finish.