Cotton fabric guide for buyers: GSM, yarn count, construction and weaves explained

Buying fabric is full of shorthand: "30s combed, 60 × 60 / 90 × 88, 58 inch", "180 GSM single jersey", "2/1 twill, sanforised". If you know what these mean, you can compare quotes, avoid surprises and get exactly the fabric your garments or home textiles need. If you don't, you're relying on the supplier's interpretation.

This guide explains the main terms for woven and knitted cotton fabric.

Woven vs knitted

• Woven fabric is made by interlacing two sets of yarn at right angles: the warp (lengthwise) and the weft (crosswise). It is stable and doesn't stretch much unless it contains elastane. Used for shirts, trousers, workwear, bed linen and denim.
• Knitted fabric is made by interlooping yarn. It stretches and is comfortable. Used for T-shirts, polos, innerwear and sportswear.

GSM: fabric weight

GSM is the fabric's weight in grams per square metre. It is the most common way to describe knitted fabric and is widely used for woven fabric too.

• Lightweight shirting and voiles: low GSM.
• T-shirts: commonly in the 140 to 200 GSM range, depending on style.
• Sweatshirts, heavy twills and canvas: much higher.

GSM affects feel, drape, opacity and cost. Always specify a GSM with a tolerance, for example ±5%.

Yarn count

Yarn count describes how fine the yarn is. In the cotton system (Ne, or "English count"), a higher number means a finer yarn. So 40s yarn is finer than 20s.

• 20s, 24s: coarser yarn for heavier fabrics.
• 30s, 40s: common for T-shirts and shirting.
• 60s, 80s and above: very fine yarn for premium shirts and luxury bed linen.

A count of "2/40s" means two 40s yarns twisted together (two-ply), giving strength and smoothness.

Combed vs carded

• Carded yarn: cotton fibres are cleaned and aligned. Economical.
• Combed yarn: an extra step removes short fibres and impurities, making yarn smoother, stronger and less prone to pilling. Costs more.

Construction (for woven fabric)

Woven fabric construction is usually written as:

Warp count × Weft count / Ends per inch × Picks per inch

For example, 40 × 40 / 132 × 72 means 40s yarn in warp and weft, 132 warp threads (ends) per inch and 72 weft threads (picks) per inch. Higher ends and picks mean a denser fabric.

Thread count, used in bed linen marketing, is the sum of ends and picks per square inch. It's useful, but count and fibre quality matter as much as the number.

Common weaves

• Plain weave: simple over-under pattern. Poplin, cambric, voile, muslin and canvas.
• Twill: diagonal lines, durable and drapes well. Denim, drill, gabardine and chino. Written as 2/1 or 3/1 twill.
• Satin (sateen): long floats give a smooth, lustrous surface. Popular for bed linen.
• Dobby and jacquard: small or large woven patterns.
• Oxford: a basket-style weave for casual shirts.

Common knits

• Single jersey: the standard T-shirt fabric.
• Pique: textured knit used for polo shirts.
• Rib: stretchy, used for collars, cuffs and fitted garments.
• Interlock: a double-knit fabric, thicker and smoother on both sides.
• Fleece and terry: for sweatshirts and loungewear.

Width

Fabric width is quoted in inches or centimetres, for example 58 inch or 150 cm. Woven widths are measured edge to edge (selvedge to selvedge). Knits may be tubular (in a tube, with width quoted flat) or open width. Width affects how efficiently pattern pieces can be cut, so state it clearly.

Finishes

Finishes change how fabric looks and behaves:

• Bleached, dyed or printed (state the dyeing type: reactive dyes are common for cotton).
• Mercerised: a treatment that adds lustre, strength and dye uptake.
• Sanforised (pre-shrunk): controls shrinkage after washing.
• Bio-washed / enzyme-washed: softer hand, less fuzz.
• Peached, brushed, wrinkle-free, anti-microbial and other special finishes.

Tests to put in your purchase order

Ask for test results, ideally from an accredited lab, for:

• GSM and width
• Dimensional stability (shrinkage) after washing
• Colour fastness to washing, rubbing (crocking), light and perspiration
• Tensile and tear strength for woven fabrics; bursting strength for knits
• Pilling resistance
• Spirality for knits (twisting of garments after washing)
• Restricted substances, such as azo dyes, if you sell in regulated markets

Many export buyers also require certifications such as OEKO-TEX Standard 100 or GOTS for organic cotton.

Fabric inspection

Before cutting, inspect fabric rolls using a points-based system (the 4-point system is common) to grade defects such as holes, slubs, stains and shade variation. Also check shade consistency between rolls and lots, because shade differences show up when panels from different rolls are sewn together.

A specification template

1. Woven or knitted, and weave or knit type.
2. Fibre content (for example 100% cotton, or cotton-elastane blend).
3. Yarn count, combed or carded.
4. Construction (ends × picks) or GSM.
5. Width.
6. Colour, dye type or print; finish.
7. Shrinkage and fastness requirements.
8. Quantity in metres or kg, delivery date and location.

Frequently asked questions

Is a higher yarn count better?

A higher count means finer yarn, which gives smoother, lighter fabric. It is not automatically better: heavier, coarser yarns suit durable fabrics like denim and workwear.

What does 30s combed mean?

It means cotton yarn of count 30 (Ne) made by the combed process, which removes short fibres for a smoother, stronger yarn. It is a common choice for quality T-shirts.

What GSM should a T-shirt be?

Many T-shirts fall roughly between 140 and 200 GSM. Lighter fabrics suit summer and promotional wear; heavier fabrics feel more premium and durable.

How do I prevent shrinkage problems?

Specify a maximum shrinkage after washing in the purchase order, ask for pre-shrunk (sanforised or compacted) fabric, and test samples before bulk cutting.

Find fabric suppliers on GlobalMart

Compare mills and traders in cotton fabrics, synthetic fabrics, denim and cotton yarn. Then post your requirement with the template above.