Convert Worsted Count to Kilograms per Metre (Nw to kg/m)

Formula

kg/m = 0.0008858118711724 ÷ Nw

Derivation from SI units:

• Nw = number of 560-yard hanks per pound, so tex = 885.8119 ÷ Nw
• The coherent SI unit of linear density: mass in kilograms per metre of length.
• Solving for kg/m: kg/m = 0.0008858118711724 ÷ Nw (a higher Nw means a lower kg/m)

Both units are defined exactly, so the factor is exact. Worsted Count definition: worsted count; Kilogram per Metre definition: kilogram per metre.

Worked examples

1. A reading of 24 Nw converts to 0.00003690882797 kg/m.
   0.0008858118712 ÷ 24 = 0.00003690882797 kg/m
2. A value of 48 Nw is 0.00001845441398 kg/m.
   0.0008858118712 ÷ 48 = 0.00001845441398 kg/m

Where it's used

Worsted Count are used for worsted wool and acrylic yarns, while kilograms per metre appear in ropes, cables and heavy tows. 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.

Worsted 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 , Worsted count.
• 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".
• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .

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