Yarn numbering systems and Conversion Table

Yarn numbering systems

Tex-System
Swicofil indicates the counts of their yarns by means of the Tex-system.
Tex Units
Term	Definition
Basic Tex Unit [tex]	Mass of yarn in grams per 1000 meters length
Decimal fraction	Mass of yarn in grams per 10'000 meters length
Decitex [dtex]	1 g / 10'000 m = 1/10 tex Decitex is the count grading for filament and spinning yarns recognized by all international bodies in the man-made fibres industry.
Decimal multiple	Mass in kilograms per 1000 meters length.
Kilotex [ktex]	1 kg / 1000 m = 1000 tex) Kilotex is used to state the counts of spinning tow and similar semi-finished and finished products.
Other numbering Systems
Count denier [den]	Mass of yarn in grams for length of 9000 meters
Metric yarns number [Nm]	Length in meters per 1 gram of mass
English cotton yarn number [Ne or ECC)]	Number of 840 yards strands per 1 English pound of mass
Wool runs	Number of 1600 yards strands per 1 English pound of mass
Wool, worsted (NeK)	Number of 560 yards strands per 1 English pound of mass
Wool, woolen measure (NeS)	Number of 256 yards strands per 1 English pound of mass
Linen Count (NeL or Lea)	Number of 300 yards strands per 1 English pound of mass
Spun Silk	Number of 840 yards strands per 1 English pound of mass
An interactive Conversion table can be found here Worsted wool is nothing to do with worsted weight yarn. Worsted wool is wool which is carded and combed so that all the fibres are parallel. Woolen measure or Yorkshire wool is carded but not combed, so is a little rougher. Worsted wool is usually very fine and used for suits and fine fabric. Hand knitting yarn is usually woolen type yarn. When quoting wool some manufacturers specify "worsted" or "woolen". Most do not!
Conversion Formulas for the various numbering systems

convert into known	tex	decitex (dtex)	denier (den)	Metric No. (Nm)	English Cotton No. (Ne)
tex		10 x tex	9 x tex	1000 tex	591 tex
decitex (dtex)	dtex 10		0.9 x dtex	10000 dtex	5910 dtex
denier (den)	den 9	den 0.9		9000 den	5314 den
Metric No. (Nm)	1000 Nm	10000 Nm	9000 Nm		0.59 x Nm
English Cotton No. (Ne)	591 Ne	5910 Ne	5314 Ne	Ne x 1.69