GSM stands for grams per square metre. It is the weight of one square metre of fabric, and it is the quickest way to tell how thick, warm and durable a hoodie or t-shirt will feel before you ever touch it. If you have ever wondered why one hoodie feels like a blanket and another feels like a sweatshirt that gave up, GSM is usually the answer.
This guide explains what GSM means in clothing, what the best GSM for hoodies and t-shirts is, and how to use it when you shop.
What does GSM mean in clothing?
Take a piece of fabric one metre long and one metre wide and weigh it. That number, in grams, is its GSM. A higher number means more fibre packed into the same area, which usually means a denser, warmer and more opaque fabric.
You will also see fabric weight written in ounces per square yard (oz/yd²), especially on American blanks. To convert, multiply oz/yd² by about 33.9. So 10.3 oz/yd² is roughly 350 GSM, and 7.1 oz/yd² is roughly 240 GSM.
GSM guide: light, mid and heavyweight
| Fabric weight | GSM range | How it feels | Typical use |
|---|---|---|---|
| Lightweight | Under 180 | Thin, drapey, can be see-through in light colours | Basic tees, summer layers, sportswear |
| Midweight | 180–240 | Soft, everyday, holds shape reasonably well | Most high-street t-shirts and polos |
| Heavyweight tee | 250–300 | Structured, opaque, drapes straight | Premium and oversized t-shirts |
| Mid hoodie | 280–350 | Comfortable, suitable year-round | Hoodies, sweatshirts |
| Heavyweight hoodie | 350–450+ | Thick, warm, holds a boxy shape | Premium streetwear hoodies and crewnecks |
What is the best GSM for hoodies?
For a hoodie you will wear from autumn to spring, 300 to 450 GSM is the sweet spot. Heavier fabric holds a clean, structured silhouette and is warm enough to wear on its own on a cool day, but too heavy can feel stiff.
- Around 350 GSM: the Baliveno Fleeced Boxy Hoodie (from £56.28) is 350 g/m² (10.3 oz/yd²) in a thick cotton-polyester blend with a boxy fit and drop shoulders.
- Around 280 GSM: the Baliveno Premium Mid-weight Hoodie (from £35) is 280 g/m² with a 100% cotton face and regular fit, a good choice for layering under a jacket.
If you run warm or want a hoodie for layering under coats, 280–350 GSM is often more comfortable. If you want the hoodie to be the outer layer, go 350 or above.
What is the best GSM for t-shirts?
For a premium t-shirt that does not cling or turn see-through, look for 240 to 300 GSM. Anything above about 250 GSM is generally sold as heavyweight.
- Baliveno Oversized Faded T-Shirt (from £30): 240 g/m², 100% carded cotton, garment-dyed and pre-shrunk, with a boxy fit and dropped shoulders.
- Baliveno Premium Heavyweight Long Sleeve Shirt (from £30): 278 g/m², 100% carded cotton, relaxed fit.
- Organic Cotton T-Shirt (from £22): an everyday organic cotton tee.
Lighter tees around 200–240 GSM still have their place, especially for training or hot weather, but they will not hold an oversized shape the same way.
Does higher GSM always mean better quality?
No. GSM tells you weight, not quality. Two fabrics with the same GSM can feel completely different depending on:
- Fibre: cotton breathes and softens with washing; polyester adds strength and shape retention; blends balance the two.
- Construction: French terry (loops inside) feels different from brushed fleece at the same weight. We cover this in our guide to French terry vs fleece.
- Finishing: washes such as vintage, mineral or snow wash soften the handle and change how heavy a garment feels.
- Stitching and trims: ribbed cuffs, double-needle seams and a well-set hood matter as much as fabric weight.
Use GSM as a first filter, then look at fibre content and construction.
How to use GSM when you shop
- Decide the job: outer layer, layering piece or summer tee.
- Pick a weight band from the table above.
- Check the fibre mix for breathability (more cotton) or shape and durability (some polyester).
- Size for the fit you want: heavyweight fabrics hang straighter, so an oversized fit looks intentional rather than sloppy.
Frequently asked questions
Is 300 GSM heavy for a hoodie?
300 GSM is a light-to-mid hoodie weight. It is comfortable year-round but will not feel as substantial as a 400+ GSM heavyweight hoodie.
Is 250 GSM a heavyweight t-shirt?
Most brands call anything from about 240–250 GSM upwards a heavyweight tee.
Does GSM change after washing?
Slightly. Cotton can shrink a little, which makes the fabric marginally denser. Washing cold and air drying keeps changes to a minimum.
Ready to feel the difference? Browse our men's hoodies, women's hoodies and t-shirts.
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