Yarn Count Systems

Yarn is too fine to specify by diameter — it is soft, compressible and often not even round — so the trade specifies it by linear density: the relationship between its length and its weight. That relationship is the yarn count, and it is the single most-quoted number in any yarn specification. This page, part of the Yarn & Spinning Guide, explains the systems in use, why they point in opposite directions, and how to convert between them with confidence. Apparel Search’s long-standing education pages treat the individual systems in depth — Yarn Count, Cotton Count and Thread Measurement — and this guide ties them together.

Two Families, Running in Opposite Directions

Indirect systems fix the weight and count the length. The count is the number of standard hanks that weigh one standard unit of weight — so the more hanks it takes to make up the weight, the finer the yarn, and the higher the number, the finer the yarn. The English cotton count and the metric count work this way; they grew up in the spinning mills, where yarn was sold by the hank.

Direct systems fix the length and weigh it. The count is the weight of one standard length of yarn — so the higher the number, the heavier and coarser the yarn. Tex and denier work this way; they suit laboratories and filament producers, who weigh a measured skein. Every conversion mistake in the trade comes from forgetting which family a number belongs to: Ne 40 is a fine yarn, 40 tex is a heavy one.

The Conversion Formulas

All four systems describe the same physical yarn, so fixed constants connect them. The constant 590.5 comes from the definition of Ne itself: one hank of 840 yards (768.1 metres) weighing one pound (453.6 grams) works out to 590.5 grams per 1,000 metres — a Ne 1 yarn is a 590.5 tex yarn, and everything scales from there.

tex = 590.5 ÷ Ne  and  Ne = 590.5 ÷ tex
Nm = 1,000 ÷ tex  and  tex = 1,000 ÷ Nm
Nm = 1.693 × Ne  and  Ne = 0.5905 × Nm
denier = 9 × tex,  so  denier = 5,315 ÷ Ne

Worked example. A mill offers a combed cotton single at Ne 30. In tex: 590.5 ÷ 30 = 19.7 tex. In metric count: 1.693 × 30 = Nm 50.8. In denier: 19.7 × 9 = 177 denier. Run it backwards to check: 590.5 ÷ 19.7 = Ne 30.0. The same yarn, four labels — which is why a specification should always name its system.

Plied Yarns and Resultant Count

When singles are plied, the count of the combined yarn — its resultant count — follows the family direction. In an indirect system, divide: a 30/2 yarn (two singles of Ne 30) has a resultant count of Ne 15, because the combined yarn is twice as heavy per hank. In a direct system, add: two 19.7 tex singles make a 39.4 tex yarn. The notation keeps both facts: the number before the stroke is the singles count, the number after it the number of plies. This is why a 2-ply Ne 30 shirting warp and a single Ne 15 yarn are close cousins in weight — the ply is rounder and stronger, but the resultant count, and therefore roughly the fabric weight, is the same. Count also feeds the twist calculation: in the cotton system, target twist is set by a multiplier applied to the square root of the count.

Older and Regional Counts

The four systems above are the living standards, but specifications and older records carry others. The worsted count counts 560-yard hanks per pound and survives in the wool trade; the woollen Yorkshire skein count uses 256-yard lengths. The thread — one turn of the reel, 55 inches in the British standard ladder — is the antique unit beneath them all, and the Apparel Search Thread Measurement page preserves the full ladder from thread to skein to hank to spindle. When an old specification quotes an unfamiliar count, the safe path is always the same: convert it to tex, the one system every other can be translated through.