You've seen "380gsm heavyweight hoodie" in a product description and wondered what it actually means for the feel and quality of the garment. GSM — grams per square metre — is the single most important fabric specification you'll encounter as a clothing brand, and understanding it will change how you design and source your products.
What Does GSM Mean?
GSM stands for grams per square metre. It measures how much one square metre of a fabric weighs in grams, which tells you its density and thickness. The higher the GSM, the heavier and denser the fabric — and generally, the more substantial and premium the garment feels in hand.
GSM is a universal measurement that applies to all fabric types: jersey, fleece, French terry, denim, canvas, and more. It's not about fibre composition — it's purely about density. A 300gsm cotton-polyester blend and a 300gsm pure cotton fabric can feel very different, even though their GSM is the same.
GSM Ranges Explained
Lightweight: 100–180 GSM
Lightweight fabrics are breathable, drapey, and ideal for warm-weather and performance garments. They're comfortable against the skin but won't offer warmth or structural weight. Think summer tees, running tops, and performance underlayers.
Best for: Summer t-shirts, athletic tops, mesh sportswear, linings
Medium Weight: 180–280 GSM
The most versatile GSM range. Fabrics here have enough body to hold structure without feeling heavy. This is the standard weight for everyday t-shirts (180–220gsm) and mid-weight hoodies (240–280gsm). A reliable, commercial sweet spot.
Best for: Everyday t-shirts, long sleeves, lightweight hoodies, basic sweatshirts
Heavyweight: 280–380 GSM
Heavyweight fabrics are where premium streetwear lives. A 340gsm hoodie has a dense, substantial hand feel that signals quality before the customer even looks at the label. These fabrics hold their shape through repeated washing and photograph with a rich, full appearance.
Best for: Premium hoodies, heavyweight crewnecks, coach jackets, quality sweatpants
Ultra-Heavyweight: 380+ GSM
Ultra-heavyweight fabrics are reserved for the most premium streetwear and workwear. A 420gsm hoodie is a deliberate statement — noticeably thick, structured, and substantial. These fabrics cost more to produce and require careful construction but deliver an unmatched premium feel.
Best for: Luxury streetwear, high-end workwear, statement outerwear
GSM Reference Table by Garment Type
| Garment | Typical GSM Range | Recommended GSM |
|---|---|---|
| Basic t-shirt | 140–200 gsm | 160–180 gsm |
| Premium t-shirt | 200–260 gsm | 220–240 gsm |
| Lightweight hoodie | 220–300 gsm | 260–280 gsm |
| Midweight hoodie | 280–360 gsm | 300–340 gsm |
| Premium heavyweight hoodie | 360–450 gsm | 380–420 gsm |
| Crewneck sweatshirt | 260–380 gsm | 300–340 gsm |
| Tracksuit bottoms | 260–380 gsm | 300–360 gsm |
| Performance jersey | 120–180 gsm | 140–160 gsm |
| Denim jeans | 280–400 gsm | 320–360 gsm |
Higher GSM Doesn't Always Mean Better
This is one of the most common misconceptions in fashion manufacturing. GSM should match the garment's intended use and seasonal positioning, not simply be as high as possible.
A 420gsm French terry hoodie is perfect for a premium winter streetwear collection. That same fabric in a performance running top would be wrong — too heavy, too hot, and too restrictive for movement. Context always matters.
Additionally, within the same GSM, quality varies enormously based on fibre quality and spinning method. A 280gsm ring-spun cotton t-shirt will feel significantly better than a 280gsm open-end spun equivalent at the same weight. GSM is one variable among several.
Always Specify GSM and Construction Together
GSM tells your manufacturer the weight, but not the fabric structure. Always pair your GSM with the construction type:
- Single jersey — smooth face, slightly textured back. Standard for t-shirts.
- French terry — smooth face, looped back. Premium sweatshirts and hoodies.
- Brushed fleece — smooth face, soft brushed back. Warm, popular in mid-range hoodies.
- Ribbed jersey — stretchy and structured. Used in cuffs, waistbands, and ribbed garments.
A complete fabric specification looks like this: "350gsm brushed-back French terry, 80% cotton 20% polyester." That gives your manufacturer everything they need to source or match the correct material.