Free tool
GSM converter and fabric weight guide
Grams per square metre is how the rest of the world specifies fabric weight; ounces per square yard is how North America does. Convert between them, then check the weight actually suits the garment.
gsm — used in Europe and Asia
oz/yd² — used in North America
1 oz/yd² = 33.906 gsm. Type into either box and the other updates.
At this weight
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Knitwear weight guide
What each weight band is normally used for in knitted garments.
| gsm | oz/yd² | Typical construction | Used for |
|---|---|---|---|
| 120–150 | 3.5–4.4 | Single jersey | Lightweight jersey tees, linings, summer baby wear |
| 150–180 | 4.4–5.3 | Single jersey | The standard tee weight — good drape, prints well |
| 180–220 | 5.3–6.5 | Jersey, pique, rib | Heavier tees, polos, kids tops that must last |
| 220–280 | 6.5–8.3 | French terry, knitted terry | Light sweatshirts, rompers, terry tees, loungewear |
| 280–340 | 8.3–10.0 | French terry, fleece, velour | Proper sweatshirts and hoodies, velour outerlayers |
| 340–420 | 10.0–12.4 | Heavy terry, sherpa, quilted knit | Heavyweight hoodies, robes, structured outerwear |
Why gsm is only half the specification
Weight tells you how much fabric there is per unit area. It does not tell you how that mass is arranged, and on knitted fabric the arrangement is most of the character.
Two fabrics at 320 gsm can behave completely differently. A dense, fine-gauge French terry at 320 gsm is firm and smooth. A 320 gsm knitted terry with a tall loop is soft, open and noticeably thicker. Same number on the spec sheet, entirely different garment.
So a proper fabric specification includes at least:
- Weight — gsm, with a tolerance (±5% is normal).
- Construction — single jersey, rib, interlock, terry, fleece, jacquard.
- Composition — fibre content and blend ratio.
- Yarn count — for example 30s combed cotton. This drives the hand feel.
- Gauge — needles per inch, which controls fineness.
- Finished width — because it affects your cutting yield.
Weight before and after finishing
Fabric gains weight through finishing. Compacting pushes the loops together, so a greige fabric knitted at 300 gsm may finish at 320–340 gsm. Always specify the finished weight, and make sure your supplier is quoting the same thing.
The conversion, if you want to do it by hand
- oz/yd² → gsm: multiply by 33.906
- gsm → oz/yd²: divide by 33.906
The number comes from converting one ounce (28.3495 g) spread over one square yard (0.836127 m²).
Once you have the weight, the fabric consumption calculator will tell you how many kilograms your order needs.
Not sure what weight to use?
Ask for a swatch.
Tell us the garment and the market, and we will send physical swatches in two or three weights so you can decide with your hands rather than a spreadsheet.