What GSM actually means (and why it matters more than you think)
GSM stands for grams per square meter - it's the standard measure of how dense a fabric is. A higher number means more fiber packed into each square inch of material, which generally translates to more warmth, more structure, and a longer lifespan. A lower number means a thinner, more breathable knit that drapes instead of holding its shape.
Most hoodies on the market land somewhere between 200 GSM and 500 GSM. That's a wide range, and the difference between each end of that spectrum is genuinely dramatic when you're wearing it. A 220 GSM pullover feels almost like a long-sleeve shirt with a pocket. A 480 GSM hoodie feels like a blanket you can walk around in.
Brands don't always list this number, which is frustrating. When they don't, you can usually judge by the listed fabric weight in ounces per square yard (oz/yd²) - multiply by 33.9 to get the rough GSM equivalent. Or just pick up the hoodie and feel the hem. Thin and floppy means lightweight; thick and the fabric holds its own fold means you're looking at something substantial.
The lightweight range: 200-280 GSM
Lightweight hoodies in this range are what most fast-fashion brands default to because they're cheaper to produce and easy to photograph. They photograph beautifully, honestly. They also wear out quickly and don't do much when the temperature actually drops.
That said, there's a real use case for them. A 240 GSM French terry or jersey-knit hoodie on a mild spring day - say, 60°F with no wind - is exactly the right call. It layers cleanly under a jacket without bunching, it won't make you sweat on a morning walk, and it's comfortable enough to wear inside without feeling like you're overheating. The issue is when people buy these expecting them to carry the weight of, say, October evenings. They won't.
If you run warm, or if you live somewhere like coastal California or the Pacific Northwest where "cool" rarely means "cold," a lightweight hoodie could genuinely be your year-round option. For most other climates, it's a March-through-May piece and maybe a September morning layer before things get serious.
The midweight range: 280-380 GSM
This is the sweet spot for probably 70% of hoodie wearers, and it's where I'd tell most people to start if they're unsure. A 300-340 GSM fleece-back cotton blend has enough substance to feel like real outerwear on a crisp early fall day while still being breathable enough that you won't die in a warm classroom or grocery store.
Early fall is genuinely tricky to dress for - mornings around 45-50°F, afternoons climbing back into the mid-60s. A midweight hoodie handles that swing better than almost any other single garment. You don't need to carry a jacket you'll regret by noon. The hoodie goes on when it's cold, comes off and ties around your waist (or gets stuffed in a bag) when it warms up, and doesn't take up half your bag in the process.
The classic Champion Reverse Weave sits around 330 GSM. Carhartt's standard pullover hoodie is in a similar range. These are not coincidentally the hoodies that have staying power for decades - the weight is functional, not just a marketing claim.
The heavyweight range: 380-500+ GSM
Deep winter is a different conversation. Once you're below 35°F and staying outside for more than a few minutes - walking a dog, waiting for the bus, standing at a bonfire - a midweight hoodie becomes a base layer, not outerwear. If you want to actually wear a hoodie as your primary layer without a coat over it, you need something in the 400-500 GSM range.
Heavyweight hoodies at this weight have real structure. The hood doesn't collapse flat in the wind. The cuffs stay put instead of folding back. And the fabric itself traps a meaningful layer of warm air against your body instead of just providing a psychological barrier against the cold. A well-made 450 GSM loopback fleece hoodie at 28°F is genuinely functional in a way a 250 GSM one simply isn't.
The tradeoff is that these are bulkier, heavier to ship, harder to layer under anything structured, and significantly more expensive. They're also usually overkill indoors - you'll roast if you wear a 480 GSM hoodie inside a heated building. So the use case is specific: outdoor cold weather, or someone who just runs cold and wants to be warm everywhere they go.
Anyway - some brands pitch their heavyweight hoodies as "capsule wardrobe essentials" and imply you can wear them everywhere year-round. That's not quite honest. They're seasonal tools, not universal ones.
A quick reference by season
- Mild spring (50-65°F): 200-280 GSM - breathable, packable, comfortable for the transition weeks
- Early fall (40-60°F, variable): 280-360 GSM - enough warmth for morning chill, not oppressive by afternoon
- Late fall / cool winter (30-45°F): 340-420 GSM - real warmth, works as standalone outerwear for short exposures
- Deep winter (below 30°F): 420-500+ GSM - or a midweight hoodie under a proper outer layer, depending on activity level
What about fabric blend?
GSM alone doesn't tell the whole story. A 320 GSM 100% cotton fleece and a 320 GSM cotton-polyester blend will behave differently - the poly blend dries faster and holds its shape longer, while the pure cotton feels softer but gets heavier when wet and takes longer to dry. For active outdoor use or unpredictable weather, blended fabrics earn their price. For everyday wear where you're not getting soaked, 100% cotton at the right GSM is hard to argue with.
French terry (smooth exterior, looped interior) is lighter-feeling than fleece at the same GSM, and it has less visual bulk. Loopback fleece gives you that traditional hoodie softness. Neither is universally better - it's just a texture and weight distribution thing worth knowing when you're comparing two hoodies at the same listed GSM.
Where to go from here
Once you know what weight you're shopping for, it's easier to ignore the noise and focus on construction quality - flat seams, reinforced drawstring channels, preshrunk fabric. If you want to browse options already sorted by use case, our hoodie collection is a reasonable place to start narrowing down.
The honest answer to "which hoodie should I buy" is almost always: figure out which season you're actually buying it for, pick the GSM range that matches, then spend as much as you can reasonably afford within that range. A well-made 340 GSM hoodie bought once beats a 240 GSM one replaced every two years, in cost and in daily use.
