Thread (yarn)

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Spool of all purpose sewing thread, closeup shows texture of 2-ply Z-twist mercerized cotton with polyester core.

Thread is a type of yarn used for sewing.


Spools of thread

Thread is made from a wide variety of materials. Following table lists common materials, a general description and what they are supposed to be good for. If your machine will sew with the thread, any thread can used for just about any purpose. This is very useful for someone who is trying to learn sewing. However, it should be remembered that where a thread is stronger than the material that it is being used to join, if seams are placed under strain the material may tear before the thread breaks. Garments are usually sewn with threads of lesser strength than the fabric so that if stressed the seam will break before the garment. Heavy goods that must withstand considerable stresses such as upholstery, car seating, tarpaulins, tents, and saddlery require very strong threads. Attempting repairs with light weight thread will usually result in rapid failure, though again, using a thread that is stronger than the material being sewn can end up causing rips in that material before the thread itself gives way.

Thread material
Material Description Purpose
Cotton Spun traditional thread general
Cotton/polyester A cotton thread with a polyester core which is slightly stretchy but retains the traditional look of cotton strength without sheen
Fusible Fuses sewn fabrics together when ironed binding and appliqué
Linen A spun thread, typically in a thicker gauge than that used for fabric garments. It may be waxed for durability and resistance to mildew. Traditional leather saddlery; leather luggage, handbags, and accessories; and beadwork.
Metallics A delicate metallic coating protected by an outer coating providing extremely vibrant color/glitter and/or texture. decoration
Nylon A transparent monofillament which can be melted by an iron. Nylon is usually stronger than polyester. strength with transparency
Polyester A synthetic blend which is stronger and stretchier than cotton with little or no lint (may be texturized) strength
Rayon Made from cellulose, but not considered to be a natural fibre because it is highly processed. Useful for obtaining bright colors, though not always color-fast. high sheen, soft texture
Silk A very fine, strong and hard-to-see thread; tends to degrade over time, however. high strength and often high sheen, used for attaching beads
Wool A thicker thread. homespun look, rougher texture, highly insulating, water absorbent
Water-soluble Dissolves when washed temporary basting


Polyester/polyester core spun thread is made by wrapping staple polyester around a continuous polyester filament during spinning and plying these yarns into a sewing thread. Core Spun Thread

Different weights[edit]

Thread gauges[edit]

Yarns are measured by the density of the yarn, which is described by various units of textile measurement relating to a standardized length per weight. These units do not directly correspond to thread diameter.

The most common weight system specifies the length of the thread in kilometres required to weigh 1 kilogram. Therefore, a greater weight number indicates a thinner thread.

American standard of thread weight (wt) was adopted from Gunze Count standard (Japan). Gunze count standard uses two numbers separated by a forward slash. The first number indicates the weight of the internal threads and the second number indicates the number of threads wrapped together to make the finished thread. It is common to wrap three strands of the same weight to make one thread (as indicated in the chart), any number of strands may be used and sometimes only two strands are wrapped together to made the finished thread. The American standard drops the specification of the number of strands which are twisted together. Therefore, it does not accurately describe thread.

Thread Weight Table
Weight Gunze Count Common Use[2]
Light 60 wt #60/3 bobbin or appliqué
Thin 50 wt #50/3 bobbin or appliqué
Regular 40 wt #40/3 Quilting
Upholstery 30 wt #30/3 Decorative
Heavy 20 wt #20/3 Decorative


A denier weight specification states how many grams 9,000 meters of the thread weighs. Unlike the common thread weight system, the greater the denier number, the thicker the thread. The denier weight system, like the common weight system, also specifies the number of strands of the specified weight which were wrapped together to make the finished thread.


Tex is the mass in grams of 1,000 meters of thread. If 1,000 meters weighs 25 grams, it is a tex 25. Larger tex numbers are heavier threads. Tex is used more commonly in Europe and Canada.

Conversion information[edit]

Thread weight conversion table

Converting From Converting To Method
Weight Denier 9000 / weight
Weight Tex 1000 / weight
Denier Weight 9000 / denier
Denier Tex denier / 9
Tex Denier tex x 9
Tex Weight 1000 / tex

For example: 40 weight = 225 denier = Tex 25. A common Tex number for general sewing thread is Tex 25 or Tex 30. A slightly heavier silk buttonhole thread suitable for bartacking, small leather items, and decorative seams might be Tex 40. A strong, durable upholstery thread, Tex 75. A heavy duty topstitching thread for coats, bags, and shoes, Tex 100. A very strong topstitching thread suitable for luggage and tarpaulins, Tex 265-Tex 290. But a fine serging thread, only Tex 13. For blindstitching and felling machines, an even finer Tex 8.

See also[edit]


  1. ^ "Thread Tips - Threads for Quilters". 2011-10-16. Retrieved 2011-11-30. 
  2. ^ "How to choose the right thread for your project and your sewing machine". Retrieved 2011-11-30.