Sheet packaging leads with a thread count, and shoppers treat higher as better. The number is real, but what it counts is narrower than the impression it creates.
The definition is simple and easily stretched
Thread count is the number of threads in a square inch of fabric, counted across both directions. On a plainly woven single-ply fabric this describes the weave density well.
The complication is multi-ply yarn. A yarn twisted from several thinner strands can be counted as one thread or as several, and counting the strands multiplies the figure.
Two fabrics can therefore carry very different numbers while having similar densities, because one counted yarns and the other counted the fibers inside them.
Fiber quality matters more than density
Long-staple cotton produces smoother, stronger yarn with fewer protruding fiber ends, which is what makes a fabric feel soft and resist pilling over time.
Short-staple cotton spun into a high thread count can produce a dense fabric that feels coarse initially and deteriorates faster with washing.
Because staple length is invisible on the shelf and thread count is printed in large type, the less informative number became the one shoppers use.
Weave structure changes the feel entirely
Percale is a plain over-under weave that feels crisp and cool. Sateen floats yarns across the surface, producing a smoother, warmer hand from the same fiber.
Sateen constructions naturally support higher thread counts, which is one reason the same fiber appears with a higher number in that finish.
Neither is better in the abstract. They are different fabrics with different properties, and choosing between them is a preference rather than a quality judgment.
Very high numbers carry a physical limit
There is a practical maximum to how many threads of usable thickness fit in a square inch before the fabric becomes stiff and loses breathability.
Figures far above that range generally indicate multi-ply counting rather than an extraordinary weave, and the resulting fabric is often heavier rather than finer.
Industry and standards bodies have pushed for single-ply counting for this reason, but labeling practice varies and the number remains inconsistently derived.
Finishing determines the first impression
Chemical softeners and mechanical finishing make a new sheet feel far better than the underlying fabric warrants, and much of that effect washes out.
Fabrics judged by touch in a store are therefore being judged partly on a treatment, which is why linen that felt excellent in the aisle can feel ordinary after several launderings.
Fiber type, staple length and weave are the durable properties, and all three are more predictive of how a sheet performs than the number on the front of the package.