Convert Yorkshire Woollen Count to Denier (NY to den)

Formula

den = 17439.42121371 ÷ NY

Derivation from SI units:

• Yorkshire woollen count = number of 256-yard skeins per pound, so tex = 1937.7 ÷ count
• 1 den = 1 g per 9000 m = 1/9 tex ≈ 1.111 × 10⁻⁷ kg/m (exact)
• Solving for den: den = 17439.42121371 ÷ NY (a higher NY means a lower den)

Both units are defined exactly, so the factor is exact. Yorkshire Woollen Count definition: Yorkshire woollen count; Denier definition: denier.

Worked examples

1. A reading of 10 NY converts to 1743.942121 den.
   17439.42121 ÷ 10 = 1743.942121 den
2. A value of 20 NY is 871.9710607 den.
   17439.42121 ÷ 20 = 871.9710607 den

Where it's used

Yorkshire Woollen Count are used for woollen-spun yarns for tweeds and blankets, while denier appear in hosiery and tights (for example 15–40 den). Both measure yarn count (linear density of yarns and fibres), but one system is the inverse of the other, so a fixed constant is divided by the value.

Yorkshire Woollen Count to other yarn count units

Frequently asked questions

Sources

• ASTM D2260, Standard Tables of Conversion Factors and Equivalent Yarn Numbers Measured in Various Numbering Systems, ASTM International , Woollen count (Yorkshire skeins).
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "yard" and "pound".
• ASTM D2260, Standard Tables of Conversion Factors and Equivalent Yarn Numbers Measured in Various Numbering Systems, ASTM International , Denier system.

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.