What is GSM? The Hoodie Fabric Weight Guide

GSM — grams per square metre — is the single most predictive number on a hoodie’s spec sheet.

It tells you how much cotton (or cotton-blend) fibre the mill knitted into each square metre of fabric, which directly determines the hoodie’s weight, opacity, warmth, drape, and long-term durability.

If you have ever ordered a hoodie online and been surprised by how thin or stiff it feels, the GSM number — or its absence from the product description — is why.

Our complete hoodie guide covers styling and construction; this article focuses exclusively on fabric weight.

Think of GSM as a hoodie’s deadlift number: the higher it is, the more seriously you can take it.

What GSM Actually Measures

Grammage is a mass-per-area measurement standardised under ISO 536 for paper and adapted for textiles under ISO 3801.

In practice, a laboratory cuts a 100 cm2 sample of fabric with a circular die cutter, weighs it on a calibrated scale, and multiplies by 100 to get the grams per square metre.

A hoodie listed at 400 GSM means the fabric alone — before cutting, sewing, trims, or the kangaroo pocket — weighs 400 grams for every square metre.

A size-L hoodie uses roughly 1.5-1.8 m2 of fabric, so the raw fabric alone weighs 600-720 grams before construction.

The relationship between Grammage and the Hoodie is direct: Grammage measures the density of the cotton or fleece from which the hoodie is constructed. Higher GSM = more fibre per unit area = heavier, thicker, more opaque, and generally more durable fabric.

There is no single correct GSM — the right number depends on what you want the hoodie to do.

The Three GSM Bands for Hoodies

Below 180 GSM, the fabric is a long-sleeve tee, not a hoodie. Above 500 GSM, you are wearing a blanket — warm but impractical for daily movement.

The 380-430 GSM band is where premium streetwear lives: dense enough to hold a structured silhouette on the body, soft enough inside to wear against skin, and heavy enough to communicate quality the moment you pick it up.

GSM vs Fabric Type: Cotton, Fleece, and French Terry

GSM sets the weight, but the fabric construction sets the feel. Two hoodies at identical 350 GSM can feel completely different:

• Fleece-backed cotton: The interior is mechanically brushed to raise a soft nap. Warm, plush, insulating. The standard for winter streetwear hoodies. Fleece provides warmth to the Hoodie through trapped air in the brushed nap.
• French terry: Unbrushed interior with visible loop-back threads. Smoother, cooler, more breathable. Better for transitional weather and layering under a jacket where you want less bulk. Same GSM as fleece, different thermal performance.
• Cotton-polyester blend (e.g. 80/20): Polyester adds wrinkle resistance and shape retention at the cost of breathability. Blended fleece pills less than 100% cotton fleece over time but does not absorb moisture as well.
• 100% combed Cotton: Combed cotton removes short fibres before spinning, yielding a smoother yarn that resists pilling. The premium option. At high GSM (380+), 100% combed cotton hoodies are heavy, soft, and breathable — the gold standard.

How GSM Affects Printing and Graphics

Screen printing on a hoodie is affected by fabric weight in ways that matter for graphic longevity.

On a lightweight 200 GSM hoodie, the print sits on a thin, flexible substrate — the ink film cracks earlier because the fabric underneath flexes more with body movement.

On a 380+ GSM heavyweight, the fabric is more dimensionally stable, meaning the ink film experiences less mechanical stress. The relationship: Screen printing durability correlates with fabric stability, which correlates with GSM.

If you are buying a graphic hoodie where the print matters, go 350 GSM or above.

How to Verify GSM When Buying Online

Not every brand publishes GSM. Here is how to verify without a lab:

1. Product description keywords: “Heavyweight” typically indicates 350+ GSM. “Lightweight” or “summer weight” = under 250 GSM. “Midweight” = 250-350 GSM. If the brand uses none of these terms, it is probably lightweight.
2. Check the weight in the spec: Some brands list a garment weight (e.g. “1.2 kg for size L”) rather than fabric GSM. Garment weight / estimated fabric area = approximate GSM. Not precise, but directional.
3. Look at the drape in model photos: A heavyweight hoodie holds a boxy, structured shape on the body. A lightweight hoodie drapes like a thick t-shirt — it follows body contours. The difference is visible even in ecommerce photography.
4. Price signal: More cotton per garment = higher raw material cost. A hoodie retailing at AUD 40 is unlikely to exceed 280 GSM. The Konahm men’s hoodie collection spans the mid-to-heavyweight range with pricing that reflects fabric weight.

GSM and Climate: Matching Weight to Weather

In Perth, Western Australia, where Konahm is based, a 400 GSM hoodie is a winter outer layer — worn over a tee from May through September.

A 300 GSM French-terry hoodie bridges autumn and spring, working under a light jacket or on its own. The local climate determines how many months per year a given GSM is wearable.

In Perth’s Mediterranean climate (mild, wet winters; hot, dry summers), the 300-400 GSM range covers 6-7 months of the year — making mid-to-heavyweight hoodies the most practical investment for Australian streetwear buyers.

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Frequently Asked Questions

What GSM should I look for in a hoodie?

350-430 GSM for a premium streetwear hoodie that holds its shape and lasts. 280-350 GSM for a year-round daily hoodie. Under 250 GSM for a lightweight layering piece.

Is higher GSM always better?

No. Above 450 GSM, a hoodie becomes uncomfortably heavy for daily wear and takes longer to dry after washing. The ideal GSM is the one that matches your climate and intended use — not the highest number on the spec sheet.

How can I tell the GSM of a hoodie I already own?

The only accurate method is a fabric punch test with a calibrated scale — not practical at home. As a rough estimate, weigh the hoodie on a kitchen scale and divide by the estimated fabric area (size L = roughly 1.6 m2).

A 650 g hoodie / 1.6 = approximately 406 GSM.

Does GSM affect how a hoodie shrinks?

Cotton shrinks regardless of GSM, but heavyweight cotton shrinks less proportionally because there is more fibre mass to absorb the same percentage of dimensional change.

A 200 GSM hoodie that shrinks 8% loses 16 g/m2; a 400 GSM hoodie that shrinks 8% loses 32 g/m2 — still substantial, but the remaining fabric is still heavy. Wash cold and air-dry to minimise all shrinkage.

What is the difference between GSM and oz/yd2?

Ounces per square yard (oz/yd2) is the imperial equivalent used by North American mills. 1 oz/yd2 = 33.9 GSM. A 12 oz hoodie = approximately 407 GSM. Australian and European brands use GSM; American brands often list oz. Multiply oz by 33.9 to convert.