Thread count is a specification invented for woven fabrics — primarily bedding — that has migrated into general textile marketing with disastrous results. It is largely meaningless for knitted fabrics, and actively misleading when applied to jersey cotton.
Understanding why requires a brief explanation of how the two fabric constructions differ.
Woven vs. knitted: different structures, different metrics
A woven fabric is made by interlacing two sets of yarns at right angles: the warp (running lengthwise) and the weft (running across). Thread count measures the number of warp and weft threads per square inch. In a well-made woven fabric, higher thread count within a reasonable range — typically 200 to 800 for sheets — can indicate tighter construction and a smoother surface.
A knitted fabric is made by interlocking loops of yarn in a continuous sequence. Jersey cotton — the construction used in T-shirts — is a single-knit fabric: one set of needles, one yarn, looping continuously. There are no warp and weft threads to count. The structural equivalent in knitted fabrics is stitch density — stitches per square centimetre — which is determined by needle gauge and yarn count but is not expressed as "thread count" by anyone who manufactures knitted textiles.
Thread count in a jersey T-shirt is a number without a referent. It describes something that does not exist in the fabric structure.
Where the myth came from
Thread count became a marketing metric for bedding in the 1990s, when manufacturers discovered that consumers would pay premiums for higher numbers without understanding what those numbers meant. The metric then contaminated adjacent textile categories — including T-shirts — because consumers had learned to associate higher thread count with quality.
Some T-shirt brands have responded to this with invented metrics: "300-thread-count cotton T-shirts," which is a category error applied to jersey construction, or "200 thread count jersey," which is meaningless because jersey is not a woven fabric. The numbers are real in the sense that someone calculated them; they are not real in the sense of describing anything about the fabric's actual structure or performance.
What actually matters in jersey
For a knitted jersey cotton T-shirt, the metrics that predict performance are:
Fibre staple length. Longer fibres produce smoother yarn with fewer surface ends, which translates to a softer hand, better colour retention, and resistance to pilling. This is measurable in millimetres at the gin.
Yarn count. Expressed as a number where higher is finer. A 40/1 yarn (single-ply, 40s count) is standard. A 60/1 or 80/1 yarn is finer, producing a more fluid, lighter fabric at the same GSM — but requires longer fibre to maintain strength at that count.
Fabric weight (GSM). Mass per unit area. Determines drape, opacity, durability under washing, and the thermal behaviour of the fabric. The most honest and useful specification for a jersey garment.
Knitting gauge. Needles per inch on the knitting machine. Higher gauge means finer needles, finer yarn, smaller loops — typically used for higher-end fabrics. Not a metric consumers usually see, but the structural determinant of fabric fineness.
None of these are thread count. If a brand is leading with thread count on a jersey T-shirt, either they do not understand their own product, or they understand it and are describing it using a metric they know consumers will misread as a quality signal.
The right question for a T-shirt is not "what is the thread count?" It is: where is the fibre from, how long is the staple, what weight is the fabric, and how does it feel after thirty washes?