Convert Yorkshire Woollen Count to Decitex (NY to dtex)

Formula

dtex = 19377.1346819 ÷ NY

Derivation from SI units:

• Yorkshire woollen count = number of 256-yard skeins per pound, so tex = 1937.7 ÷ count
• 1 dtex = 1 g per 10 000 m = 0.1 tex = 10⁻⁷ kg/m (exact)
• Solving for dtex: dtex = 19377.1346819 ÷ NY (a higher NY means a lower dtex)

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

Worked examples

1. A reading of 10 NY converts to 1937.713468 dtex.
   19377.13468 ÷ 10 = 1937.713468 dtex
2. A value of 20 NY is 968.8567341 dtex.
   19377.13468 ÷ 20 = 968.8567341 dtex

Where it's used

Yorkshire Woollen Count are used for woollen-spun yarns for tweeds and blankets, while decitex appear in polyester and nylon filament yarns (for example 167 dtex). 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".
• ISO 1144, Textiles — Universal system for designating linear density (Tex System), International Organization for Standardization , Tex system.

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