Sweater
Yarn Count Calculation
Dr. Jimmy Lam
Institute of Textiles & Clothing
The Hong Kong Polytechnic University
Yarn Count
• Two Systems, namely Indirect
System and Direct System
• In sweater calculation, we normally
converted both into Metric system
(Nm)
Indirect System
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Normally uses for cotton yarn and most of
cotton blended yarns (acrylic cotton, ramie
cotton yarn)
Symbol: NeC or ECC or ‘s
Definition: Number of unit length per unit mass
(variable length, constant weight)
The higher the count number, the finer the
yarn.
The lower the count number, the coarser the
yarn.
Indirect System
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Cotton Count (NeC) = Length (yd) x
840 /weight (pound)
Metric system (Nm)=Length (km)
per weight (1 kg)
Conversion 1 Nm =NeC X 1.693
Indirect System
Example
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A skein of 26,880 yards weight 1
pound, calculate its English count
and Metric equivalent.
Answer:
Cotton Count=26,880/840 =32NeC
Metric (Nm) =32 x 1.693 =54Nm
Direct System
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Normally uses for continuous filament yarns
such as viscose rayon, polyester, etc.
Definition: Number of mass per unit length
(Variable weight and constant length)
The higher the count number, the coarser the
yarn.
The lower the count number, the finer the yarn.
Direct System
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Denier (Td) = weight (g) per length (m) x
9000
Tex = weight (g) per length (m) x 1000
Conversion to Metric System (Nm)
Nm=9000 /denier (Td)
Nm=1000/Tex (Tt)
Conversion between Tex and Denier
Tex=Denier/9
Direct System
Example
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A skein of 300 meters of filaments
viscose rayon yarn weights 10
grams, calculate its denier and
metric equivalent.
Answer:
Denier = 10 /300 x 9000 = 300Td
Metric (Nm) = 9000/300 =30Nm
More Example
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Ex1: 20/2 NeC 55% acrylic, 45% cotton
yarn
Metric System = 2/(20 x 1.693)
=2/34Nm =17 Nm
Ex2: 11/2 NeC 55% ramie, 45% cotton
yarn
Metric System= 2/(11 x.1693)
=2/18.6Nm
Resultant Count
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Yarn produced by the combination of two or
more single yarns is used in many textile
structures in order to achieve effects which
may not be readily obtained by single yarn.
In an indirect system, the resultant count is
equal to the sum of the reciprocals of the
component yarns.
1/N = 1/N1 + 1/N2 where N is resultant count
and N1 and N2 are component yarns
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Resultant Count
Example
A two fold yarn (ie yarn made by twisting two
single yarn together) is found to have one
300 Td 100% viscose rayon yarn and one 20/1
NeC 100% cotton yarn. Calculate the
equivalent single count in metric system.
Answer:
Metric (Nm) for rayon =9000/300=30Nm
Metric (Nm) for cotton= 20 x 1.693
=33.87Nm
Resultant Count 1/N = 1/30 + 1/33.87
=1/15.9Nm
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Yarn component calculation
A sweater is knitted with two
different yarns. One end is 32/2 NeC
100% cotton yarn and the other end is
of plated 84 Denier (Td) 85% nylon,
15% lycra yarn. Calculate:
A) The resultant count of the
component yarn;
B) The percentage by weight of
various yarn used;
C) The fibre content of the sweater
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Yarn component calculation
Answer
A) Resultant Count:
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Cotton =32/2 x 1.693 =17 x 1.693=27Nm
Nylon and lycra=9000/84=107Nm
Resultant Count 1/N =1/27 + 1/107
=1/21.6Nm
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Cotton=1/27Nm =1/27kg =0.037kg
Nylon and lycra =1/107Nm =1/107kg =0.009kg
Total weight of two components:0.037+0.009 =0.046kg
Percentage of Cotton: 0.037/0.046x100% =80%
Percentage of Nylon/lcyra =0.009/0.046x100%= 20%
B) Percentage by weight of two components in
every km:
Yarn component calculation
Answer
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c) Fibre composition of the component
yarns:
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Cotton =80% x 100%= 80%
Nylon = 20% x 85% = 17%
Lycra =20% x 15% =3%
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The fibre content of the sweater is:
80% cotton, 17% nylon and 3% lycra