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HomeFabric knowledge › Fabric weight explained: GSM, oz/yd² and how to specify it
Fabric knowledge

Fabric weight explained: GSM, oz/yd² and how to specify it

Updated 2026-09

On this page
  • GSM is weight per area, not thickness
  • Converting to ounces
  • Tolerance is the part buyers forget
  • Picking a weight

GSM is weight per area, not thickness

GSM means grams per square metre. A 120 GSM poplin and a 120 GSM jersey weigh the same per square metre, but one is a shirt body and the other a T-shirt — weight alone does not tell you the hand. It does, however, predict warmth, opacity and how a garment drapes.

Converting to ounces

Buyers in the US still quote oz/yd². The conversion is fixed:

1 oz/yd²= 33.906 GSM
100 GSM≈ 2.95 oz/yd²
200 GSM≈ 5.90 oz/yd²

We publish GSM on every specification because it is the unit our lab actually measures; the ounce figure is derived, not estimated.

Tolerance is the part buyers forget

A spec that says “150 GSM” with no tolerance is incomplete. Finishing (sanforising, coating, brushing) shifts the number, so we state a tolerance band and measure against it. When you compare two mills, compare the band, not just the headline number.

Picking a weight

Not sure what your garment needs? Send the end use and we will suggest a starting weight on the quote request.

Common questions

Is a higher GSM always better?

No. Higher means heavier and usually warmer or more opaque, but it also means stiffer and more expensive per metre. The right weight follows the garment, not a scoreboard.

Why do some specs list coated and uncoated weight separately?

Because coating or lamination adds grams that are not cloth. Quoting them together hides the real fabric weight; we separate them so you can compare like for like.

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