How to Choose Knitted Fabric GSM and Construction
GSM is usually the first number buyers ask about, but on its own it says little about how a knitted fabric will look, stretch or wash. This guide is for brands, garment makers and fabric buyers who want to choose knitted fabrics with more confidence. It explains the difference between weight and construction, gives typical GSM ranges for common knits, and ends with a checklist for specifying a knitted fabric order.
GSM and Construction Are Two Different Questions
GSM stands for grams per square metre. It tells you how much material sits in one square metre of fabric, so it is a useful shorthand for warmth, opacity and, because knitted fabric is often priced by the kilogram, cost. It does not tell you how that material is arranged.
Construction describes the arrangement: single knit or double knit, the stitches used, the machine gauge and the loop length. A 200 GSM single jersey and a 200 GSM interlock weigh the same, yet the jersey is thinner, curls at the edges and has a distinct face and back, while the interlock is thicker, smooth on both sides and more stable.
The practical rule is to choose the construction first, based on how the product must look and behave, and then set the GSM within the range that construction typically supports.
Common Knit Constructions and Typical GSM Ranges
The table summarises the knitted structures buyers use most often. The GSM bands are typical industry ranges for cotton-rich fabrics, not fixed limits; actual values depend on yarn, gauge, finishing and the mill.
Within each band, the lighter end suits warm weather and layering, while the heavier end adds opacity, warmth and structure.
| Construction | Structure | Typical GSM | Typical end uses | Handle and behaviour |
|---|---|---|---|---|
| Single jersey | Single knit; V-shaped loops on the face, half-loops on the back | Typically 120–220 | T-shirts, bodysuits, light sleepwear | Light and smooth; stretches easily across the width; cut edges curl |
| Interlock | Double knit; two 1x1 rib structures knitted together | Typically 170–260 | Babywear, pyjamas, leggings, fitted basics | Smooth on both sides; soft, stable and lies flat |
| Rib (1x1, 2x2) | Double knit; face and back stitches alternate in columns | Typically 160–300 | Neckbands, cuffs, fitted tops, bodysuits | High widthwise stretch with the best natural recovery |
| French terry | Single knit with an extra loop yarn on the back (two- or three-thread) | Typically 200–350 | Sweatshirts, joggers, pyjamas, baby layers | Flat face, soft loops inside; more body and warmth than jersey |
| Pique | Single knit with tuck stitches that form a textured face | Typically 180–240 | Polo shirts, sportswear, blankets | Textured, airy surface; holds its shape; less stretch than jersey |
How Yarn Count and Composition Change the Fabric
Two fabrics with the same construction and GSM can still feel very different because of the yarn. Count, spinning method and fibre content all influence softness, surface clarity, pilling and price.
Yarn count and spinning
Cotton knitting yarns are usually described in the English count (Ne), where a higher number means a finer yarn. Ne 30/1 is a common choice for T-shirt jersey, while Ne 20/1 gives a heavier fabric and Ne 40/1 a finer, smoother one that suits detailed printing.
Combed and compact yarns contain fewer short fibres than carded or open-end yarns, which typically means a smoother surface and less pilling, usually at a higher cost.
Fibre composition
- Cotton: breathable and soft on the skin; the default for babywear, T-shirts and sleepwear, but it needs good finishing to control shrinkage.
- Organic cotton: performs like conventional cotton; certified chain-of-custody documents are usually required, so confirm them at the start.
- Modal: smooth and drapey; often blended with cotton for sleepwear and loungewear.
- Bamboo-based viscose: soft with a cool feel; labelling rules for bamboo fibres differ between markets.
- Elastane: a small percentage improves recovery and fit, but it changes heat-setting, shrinkage behaviour and price.
Stretch, Recovery and Shrinkage
Knitted fabrics stretch because their loops can open and close, mostly across the width. Recovery depends on construction and fibre: rib recovers best, interlock is stable, and single jersey stretches easily but can lose shape at necklines without elastane or a rib trim.
Shrinkage is the most common complaint with cotton knits: knitting and dyeing put tension into the fabric, and washing releases it. Compacting and relaxed drying reduce residual shrinkage, and fabrics with elastane also need heat-setting.
A typical specification for cotton knits is a residual shrinkage limit of around 5% in length and width, with tighter limits for premium programmes. The figure only means something with a stated test method, such as ISO 6330 washing with ISO 5077 measurement, or AATCC 135 for many US buyers. Single jersey should also be checked for spirality, the twist that moves side seams after washing.
Matching the Fabric to the End Product
With the options clear, the choice comes down to a few practical questions. Answering them before sampling saves revision rounds.
- Season: light single jersey for summer and layering; interlock, French terry or heavier rib for cooler months.
- Silhouette: jersey drapes, interlock and pique hold their shape, and rib hugs the body.
- Decoration: smooth, dense faces such as interlock or fine-gauge jersey give the sharpest print detail.
- Making-up: single jersey curls at cut edges, which slows cutting and sewing; double knits are easier to handle.
- Cost: a heavier fabric uses more yarn per square metre, so a higher GSM usually raises the cost of each garment.
How to Specify a Knitted Fabric Order
A clear specification reduces misunderstandings and helps the mill quote accurately. Most knitted fabric quotations need the points below.
- 1Product and construction
Describe the end product and name the construction, for example 1x1 rib for cuffs or interlock for a baby bodysuit. Send a physical reference if you have one.
- 2Composition and yarn
State the fibre content and, where known, the yarn count and spinning type. Mention any certification you need, such as organic or OEKO-TEX®, at this stage.
- 3Finished GSM and tolerance
Give the GSM after dyeing and finishing, not the greige weight, with a tolerance; around ±5% is typical.
- 4Width and form
Specify the usable width your cutting plan needs and whether the fabric should be open-width or tubular.
- 5Colour, print and finish
List colours with references, the print method if printed, and finishes such as softening or peaching.
- 6Performance and testing
Agree limits and test methods for shrinkage, spirality, colour fastness and pilling.
- 7Quantities and timing
Give the quantity per colour, the total quantity and the target delivery date so that minimums and lead times can be checked in the quotation.
Developing Knitted Fabrics with DRU Textile
DRU Textile produces knitted and woven fabrics in Denizli, Turkey, drawing on more than 60 years of textile manufacturing experience and over 10 years of exports. GSM, width and construction are agreed for each project. Our range includes single jersey, interlock, rib and kaşkorse, alongside terry and muslin, and our two-thread French terry is used in breathable 1.0 TOG children’s pyjamas.
Fabrics are plain-dyed or printed with reactive, pigment or digital printing, in cotton, organic cotton, modal, bamboo and blends, with blend ratios agreed per project. They are produced in line with OEKO-TEX® standards; certificate details are shared on request. Through Custom Fabric Development we build and sample a fabric around your brief, and through Wholesale Roll Fabric Supply we deliver the agreed specification by the roll. Per-colour and total minimums are confirmed with each quotation.
Frequently Asked Questions
Discuss Your Knitted Fabric Specification
Share your end product, target GSM and preferred construction, and we will come back with suitable fabric options and a project-based quotation.