Fabric fundamentals
Fabric GSM explained: how weight changes drape, durability and cost
GSM is the first number most buyers quote and the one most often misunderstood. Here is how weight actually changes drape, opacity, durability and cost — with the bands we use in our own mill.
What GSM actually measures
GSM stands for grams per square metre. A 160 gsm jersey means one square metre of the finished cloth weighs 160 grams. It is a mass measurement, and nothing more — it says nothing on its own about yarn quality, weave density or durability.
This matters because buyers often treat GSM as a proxy for quality. Two 180 gsm cotton shirtings can differ by 40% in cost and behave nothing alike: one may use fine 80s combed yarn in a dense plain weave, the other coarser 20s yarn in a loose construction. The first feels crisp and holds a collar; the second feels soft and drapes but pills.
Weight bands by garment type
These are the ranges we ship most often. They are starting points, not rules — a heavyweight tee trend can push jersey to 240 gsm, and a summer shirt can drop to 90 gsm.
| Garment | Fabric | Typical gsm | Notes |
|---|---|---|---|
| Summer shirt | Cotton poplin / voile | 90–130 | Below 100 gsm needs a lining or print to stay opaque |
| Dress shirt | Combed poplin | 110–140 | 120 is the commercial sweet spot |
| T-shirt | Single jersey | 150–180 | 220–240 for heavyweight boxy fits |
| Hoodie | French terry / fleece | 280–340 | 320+ for winter-weight brushed back |
| Chinos | Cotton twill | 220–280 | Higher weight for workwear |
| Jeans | Denim | 340–475 | 10 oz ≈ 339 gsm, 14 oz ≈ 475 gsm |
| Light jacket | Softshell / taslan | 120–320 | Membrane layers add weight without bulk |
| Linen dress | Washed linen | 160–200 | 260 for structured silhouettes |
Why two fabrics at the same GSM feel different
Yarn count sets the surface character. Finer yarns at the same weight mean more ends and picks per inch, so the cloth is denser, smoother and more expensive. Coarser yarns give texture, airiness and a lower price.
Finish changes the hand as much as the construction. A compacted knit at 160 gsm feels denser than an uncompacted one because the loops are closer together. A garment-washed linen at 180 gsm feels lighter than a rigid 180 gsm linen because washing relaxes the weave.
For this reason, always specify weight on the finished fabric and ask for a finished-sample test report, not a greige figure. Greige-to-finished weight can shift 5–12% after desizing, dyeing and washing.
How weight drives cost per metre
Within one construction, price tracks weight almost linearly because you are buying fibre mass. Moving a cotton jersey from 160 to 200 gsm adds roughly 25% to the yarn cost, and yarn is typically 55–65% of the FOB price.
Across constructions the relationship weakens. Linen at 180 gsm costs more than cotton canvas at 320 gsm, because fibre price and processing differ far more than the weight difference. Never compare quotes across fibre types on price per gram.
- Same construction: price roughly proportional to GSM.
- Different fibres: fibre price dominates, not weight.
- Finishes (DWR, calendering, bonding) can add 10–30% independent of weight.
- Below 100 gsm, processing cost per metre rises because the fabric is harder to run.
Matching weight to market and climate
For Northern European and North American autumn/winter ranges, buyers usually go 10–15% heavier than for Southern Europe. For the Gulf and wider Middle East, weight matters less than fibre and breathability: a 180 gsm linen is cooler than a 150 gsm polyester because of how the fibre handles moisture.
If you are developing one style for multiple markets, keep the construction and change the finish. A 160 gsm jersey with a dry hand for the Gulf and a peached finish for Northern Europe lets you run one fabric base and two SKUs, which keeps minimums achievable.
Frequently asked
Is higher GSM always better quality?
No. GSM measures weight per square metre, not quality. Yarn count, weave density, fibre length and finishing determine quality; a well-made 140 gsm poplin outperforms a loose 180 gsm one.
How do I convert ounces to GSM for denim?
Multiply ounces per square yard by 33.91. So 10 oz denim is about 339 gsm, 12.5 oz is about 424 gsm, and 14 oz is about 475 gsm.
Should GSM be measured before or after washing?
Specify it on the finished, dyed fabric after the final wash. Greige weight is typically 5–12% higher, so quoting greige GSM will make the delivered cloth feel lighter than expected.