You see it on premium hoodie product pages: "400gsm brushed-back French terry." It is the spec that defines the heavyweight category. But what does 400gsm actually mean, why does it matter, and how do you know if a brand is using the number honestly? This guide breaks it down.
GSM stands for grams per square metre. It is the weight of one square metre of finished fabric. A 400gsm hoodie is built from fabric where one square metre weighs 400 grams. A standard hoodie at 260gsm contains 260 grams per square metre. The difference, 140 grams per square metre, or 54% more material, is what produces the heavyweight feel, drape, warmth, and longevity.
| GSM | Category | Feel |
|---|---|---|
| 180-220 | Lightweight | Summer hoodie, thin layer |
| 240-300 | Regular | Standard hoodie, soft drape |
| 320-380 | Heavyweight | Structured, falls heavy |
| 380-420 | Ultra-heavyweight (400gsm sits here) | Dense, coat-adjacent |
| 420+ | Ultra+ | Almost rigid, statement piece |
A 400gsm hoodie sits at the top of mainstream premium. Above this you enter statement-piece territory where the fabric becomes almost outerwear in its own right.
A typical hoodie uses 0.8 to 1.4 square metres of fabric depending on size and cut. At 400gsm, that means each hoodie contains 320 to 560 grams of finished fabric, compared with 208 to 364 grams at 260gsm. The fabric input alone goes up by about 54%.
That extra material affects every cost downstream:
This is why mass-market hoodies sit at 240-280gsm. The math at the lower weight allows for €25-€40 retail. The math at 400gsm requires €100+ retail to maintain margin. Brands marketing "premium heavyweight" at sub-€60 are almost always selling lower GSM with premium-sounding marketing.
The difference between holding a 260gsm regular hoodie and a 400gsm heavyweight is unmistakable in person:
GSM alone is not the full picture. A 400gsm hoodie in a poor fibre blend or with cheap construction can still be a worse garment than a 360gsm hoodie built properly. The number to look for, combined with GSM:
Composition, A premium 400gsm hoodie typically runs 80% cotton / 20% polyester. A budget 400gsm hoodie might run 50/50 or 60/40, producing a heavier but less natural feel. The cotton-poly ratio is the second number that matters as much as GSM.
Construction type, 400gsm in flat French terry feels different from 400gsm in brushed-back French terry. Brushed-back has the mechanically opened pile on the inside that traps air and increases warmth perception. It is the construction that produces the soft luxurious hand-feel of true premium heavyweight.
Trim spec, Even a 400gsm body fabric falls apart if the cuffs and hems aren't built to match. Premium 400gsm hoodies use ribbed cuffs and hems at 500-600gsm, higher than the body, to provide enough density for permanent shape retention.
For the full fabric primer, see The Activewear Fabric Guide.
Some brands publish exact GSM on every product page. Some publish a vague range. Some say "heavyweight" without any number at all. The marketing language tells you what the brand thinks of the customer:
Depends on use case. A 400gsm hoodie is overkill for indoor wear in summer. A 260gsm is undersized for outdoor winter use. The sensible matching:
| Use Case | Appropriate GSM |
|---|---|
| Summer layering, indoor wear | 180-240 |
| Spring/autumn daily wear | 240-320 |
| Cold weather outer layer | 320-400 |
| Winter outer layer, statement piece | 400+ |
A 400gsm hoodie sits at the upper end, built for cold conditions, structured silhouette wear, and longevity. It performs as a transitional outer layer in winter for many climates, and as a heavy mid-layer in extreme cold.
If built properly, with matching premium composition, brushed-back construction, ribbed trim, flatlock seams, and bartack reinforcements, a 400gsm hoodie survives 5-10 years of regular wear. The fabric resists pilling because the cotton content is high; the cuffs hold shape because the rib is denser than the body; the seams don't pull because they sit flat instead of forming raised ridges.
Compared with a 260gsm regular hoodie at 1-2 years of service life, the 400gsm premium delivers 4-5x more wear cycles. At €140 for the premium vs. €40 for the regular, the cost per wear is similar or lower for the premium over the actual lifespan of both garments.
Every Catar Cottega hoodie is built to a single published spec: 400gsm brushed-back French terry, 80% cotton / 20% polyester, double-layer hood, ribbed cuffs and hems at 500gsm, flatlock seams with bartack reinforcement at every stress point. The numbers are on every product page because the numbers are what the hoodie actually is.
400gsm is not a marketing buzzword. It is a structural spec. Built to outlast the trend.
For the deeper breakdown on heavyweight construction, see The Complete Guide to Heavyweight Hoodies and Heavyweight Hoodie vs Regular Hoodie.
Related reading:
Want the deep dive? Read our complete guide to seamless activewear covering knitting tech, fabric science, sizing and care.
