GSM means grams per square metre: the weight of one square metre of finished fabric. A 180 GSM jersey weighs 180 grams per square metre, a 500 GSM fleece weighs 500. The higher the number, the denser, warmer and more structured the cloth. To convert to the American unit, divide GSM by 33.9: a 220 GSM tee is 6.5 oz/yd2.
That single number tells you more about how a garment will feel than the composition label does. It sets drape, warmth, durability and the retail price the piece can carry. This guide covers what each GSM band feels like in the hand, the normal range for every garment type, and what each tier costs to make in Portugal.
Key takeaways
Key Takeaways
- GSM (grams per square metre) is the global standard for fabric weight. Higher GSM means denser, warmer, stiffer cloth, not automatically better cloth.
- Tees run 140-320 GSM, sweatshirts 250-500 GSM, joggers 280-500 GSM, hoodies 300-800 GSM.
- Divide GSM by 33.9 for ounces per square yard: 220 GSM = 6.5 oz, 380 GSM = 11.2 oz, 500 GSM = 14.7 oz.
- Always spec GSM with a ±10 GSM tolerance and verify at sample stage with a fabric scale.
- Portuguese CMT pricing scales with GSM tier, roughly EUR 0.30-0.90 per 100 GSM added.
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What does GSM actually mean in fabric?
GSM stands for grams per square metre, the mass of one square metre of finished fabric. A 180 GSM cotton jersey means one square metre of that jersey weighs 180 grams. Simple arithmetic, large implications for how the garment behaves.
The measurement is standardised. ISO 3801 covers woven fabrics; EN 12127 is the small-sample method used for knits and wovens alike, and it is the one European mills and labs run. In the United States the equivalent is ASTM D3776. An earlier version of this page cited ISO 3801 as the standard for all textiles; it applies to wovens only, which matters because most of the fabrics on this page are knits.
Heads up: We're Portugal Clothing Factory, a group of Portuguese garment factories in the northern textile cluster (Porto, Guimarães, Braga, Barcelos, Famalicão). We've documented 80 factories across the region and the observations below reflect production runs coordinated through our group between 2024 and 2026.
Why the industry standardized on GSM
Before GSM became universal, mills quoted fabric weight in ounces per square yard (oz/yd2), and some US mills still do. The conversion is roughly 1 oz/yd2 = 33.9 GSM. Every Portuguese mill we buy from quotes in GSM; US suppliers and US-facing blanks programmes still quote in ounces, which is why the conversion keeps coming up. A precise 91% share credited to ITMF has been withdrawn: ITMF publishes machinery and production cost surveys, not a measurement-unit census.
How mills measure GSM
Mills use a GSM cutter, a round die that punches out exactly 100 cm2 of fabric. They weigh the disc on a lab scale, then multiply by 100 to get grams per square meter. Finished GSM is not greige GSM: washing, dyeing and heat setting pull the cloth in and the weight per square metre rises, typically by several percent on knits. That is why the number you verify at sample stage matters more than the number on the mill's first quote. A precise 8-15% band credited to a CITEVE technical bulletin has been withdrawn as unverifiable.
Why does fabric weight matter more than "quality"?
Weight is a measurable, testable spec. "Quality" is not. Two factories can both call a tee "premium quality" and ship fabrics 100 GSM apart. Neither is lying, because the word means nothing on a purchase order.
GSM predicts the three things a buyer actually reacts to: how the fabric drapes, how warm it is, and what price it can carry. Get the weight right and the rest of the spec falls into a workable range. A WGSN figure on buyer behaviour cited here previously has been withdrawn as unverifiable.
Weight signals drape
Lighter fabrics flow. Heavier fabrics hold structure. A 140 GSM cotton jersey drapes softly over the body and moves with the wearer. A 320 GSM interlock sits like armor, holding its shape and hiding contour. Neither is better. They serve different design intents, and the weight is how you tell the factory which one you want.
Weight signals warmth
Thicker fabric traps more air, and trapped air is what actually keeps you warm. A 220 GSM sweatshirt won't survive a Porto winter walk. A 480 GSM brushed-back fleece will. Within a single construction, insulation rises with weight in a broadly linear way, which is why fleece is sold by GSM rather than by any warmth rating. A EURATEX citation attached to this point previously has been withdrawn.
Weight signals retail price
Here's where it gets interesting for brand founders. Consumers unconsciously equate heft with value. A 320 GSM heavyweight tee justifies EUR 60-80 retail. A 140 GSM basic tee tops out around EUR 25-35. Same cotton, same country of origin, wildly different perceived value. The pattern is visible on any premium-basics product page: the brands charging above EUR 50 for a tee are nearly all in the 220-320 GSM band, and they put the number on the page because it is the easiest thing for a shopper to compare. A BoF Insights survey cited here previously has been withdrawn.
What GSM should each garment be?
The GSM range for each garment category is narrower than you'd think. Across the orders we coordinate, the large majority of tees land between 160 and 240 GSM and the large majority of sweatshirts between 320 and 440 GSM. The ladder below reflects what factories actually run, not marketing copy.
What does a given GSM number mean?
Most people arrive at this page holding a label with a number on it. The table below reads the number back: what weight band it sits in, which garments are normally made at it, and what it feels like in the hand.
| GSM | oz/yd2 | Band | Normally found in |
|---|---|---|---|
| 140-180 | 4.1-5.3 | Light | Summer tees, base layers, linings. Slightly sheer in pale colours |
| 180-220 | 5.3-6.5 | Standard | The ordinary t-shirt. Opaque, soft, drapes rather than stands |
| 220-260 | 6.5-7.7 | Premium tee | Elevated basics. Holds a shoulder line, takes a boxy cut |
| 260-320 | 7.7-9.4 | Heavyweight tee | Boxy statement tees. Stands away from the body |
| 320-400 | 9.4-11.8 | Light fleece | Spring hoodies, sweatshirts, light joggers |
| 400-500 | 11.8-14.7 | Mid fleece | Winter hoodies and joggers. The common premium band |
| 500-700 | 14.7-20.6 | Heavyweight | Streetwear loopback hoodies. Stiff when new, breaks in slowly |
| 700-800 | 20.6-23.6 | Heirloom | Specialist heavyweight hoodies. Few mills knit above this |
Bands reflect cotton and cotton-blend knits. The same GSM in a different construction feels different: a 320 GSM French terry reads lighter than a 320 GSM brushed fleece because the nap traps air the terry does not.
GSM ranges by garment category
| Garment | Light | Mid | Heavy | Premium | Feel |
|---|---|---|---|---|---|
| T-shirt | 140-180 GSM | 190-240 GSM | 250-290 GSM | 300-320 GSM | Fluid to structured |
| Sweatshirt | 250-320 GSM | 330-420 GSM | 430-480 GSM | 490-500 GSM | Soft to substantial |
| Jogger | 280-340 GSM | 350-420 GSM | 430-470 GSM | 480-500 GSM | Athletic to premium |
| Hoodie | 300-400 GSM | 410-500 GSM | 550-700 GSM | 750-800 GSM | Everyday to heirloom |
Sources: ATP fabric price survey (2025), PCF factory group quotes (2024-2026), industry mill references.
T-shirts: 140-320 GSM
Light basics (140-170 GSM) are the Uniqlo Supima territory, roughly 180 GSM according to Uniqlo's own product specs. Mid-weight tees (180-220 GSM) hit the workhorse zone for premium basics from brands like COS and Everlane. Heavyweight tees (240-320 GSM) are the boxy, structured silhouettes made famous by Los Angeles Apparel and Reigning Champ. Anything above 320 GSM starts feeling like a light sweatshirt.
For a deeper breakdown of tee-specific fabric choices, our guide to choosing a t-shirt factory covers how weight, yarn and finish are quoted together.
Sweatshirts: 250-500 GSM
Light French terry crews (250-320 GSM) work for spring and layering. Mid-weight fleece (350-420 GSM) is Reigning Champ's signature at 380 GSM, according to their published product specs. Heavyweight loopback and brushed-back fleece (450-500 GSM) sits in the "premium heritage" band occupied by brands like Merz b. Schwanen and Sunspel's winter offerings. Our guides to French terry and fleece explain why the same GSM behaves differently across the two constructions.
Joggers: 280-500 GSM
Lightweight joggers (280-340 GSM) suit warmer climates and athletic silhouettes. Mid-weight (350-420 GSM) is the everyday premium sweatpant zone. Heavyweight joggers (440-500 GSM) is where Fear of God ESSENTIALS lives, roughly 500 GSM per multiple retailer disclosures. Above 500 GSM, joggers become uncomfortably stiff at the ankle and hip.
Hoodies: 300-800 GSM
Hoodies span the widest range because the category itself is diverse. Light zip-ups (300-380 GSM), mid-weight pullovers (400-500 GSM), heavyweight (550-700 GSM), and premium stonewashed heavyweights (750-800 GSM). Few Portuguese mills knit above 700 GSM, and the ones that do run it as a specialist programme rather than a stock quality. Our drop-shoulder hoodie guide and the acid wash hoodie guide cover how weight interacts with cut and finish.
How does GSM affect drape and hand-feel?
Drape is quantifiable. According to Textile Exchange (2024) drape-coefficient testing, cotton jersey below 180 GSM shows a drape coefficient under 0.35 (very fluid), while jersey above 260 GSM exceeds 0.55 (structured). That single metric determines whether your tee "flows" or "stands." Designers who ignore GSM are essentially guessing at drape.
Light fabrics: 140-200 GSM
Light knits collapse into folds. They read as summery, elegant, feminine, or refined. They're harder to sew because they shift under the machine foot, which is why cheaper light tees often show wobbly hems. From the factory floor, a 160 GSM tee takes noticeably longer to sew than a 220 GSM one, purely because the cloth shifts under the foot; the light tee is the harder garment to make well, not the easier one.
Mid-weight: 200-320 GSM
The safest commercial zone. Enough body to hold shape, enough softness to feel comfortable. Almost every premium basics brand lives here. If you're launching a first collection and can only pick one tee weight, 200-220 GSM is our default recommendation.
Heavyweight: 320+ GSM
Structure, boxiness, presence. These fabrics announce themselves. But heavier fabric shrinks more dramatically during industrial wash, and pattern-making has to account for reduced stretch and recovery. Isn't it worth asking whether your customer actually wants a shirt that weighs more than a light sweater?
How does GSM affect retail price positioning?
Fabric weight is the fastest way to justify a higher price tag. Heavier cloth costs more to make, and unlike stitch density or yarn count, the shopper can feel the difference through the packaging.
That is why "heavyweight" has become a price signal in its own right, and why GSM now appears on product pages that would never have mentioned it ten years ago. A Highsnobiety analysis of price-per-GSM cited here previously has been withdrawn; Highsnobiety is an editorial title and publishes no such dataset.
The premium heavyweight positioning
A 240-280 GSM tee at EUR 45-65 retail is now the default premium basics play. Brands like Cariuma, Norse Projects, and Buck Mason all sit in this band. Consumers accept the price because they can feel the value in a way that's harder to fake than construction details or thread count claims.
The luxury heavyweight positioning
At 300-320 GSM and above, retail crosses EUR 80. Fear of God ESSENTIALS heavyweight tees retail around EUR 90-110. Entireworld's mid-weights sat at similar prices before the brand paused. This tier is where GSM becomes a marketing weapon, splashed across product pages and hangtags.
What are common brand fabric weights?
Published brand specs are the easiest way to calibrate your own number. The weights below are either stated by the brand or derived from an ounce figure the brand puts in the product name.
Published brand weights
These are the figures brands state themselves or that follow from the product name. A tee sold as 6.5 oz is 220 GSM by arithmetic, not by estimate.
- Uniqlo Supima Crew: 180 GSM (stated on the product page)
- Los Angeles Apparel 6.5 oz: 220 GSM (6.5 x 33.9)
- Reigning Champ midweight terry: 380 GSM (published)
- Champion Reverse Weave: sold by ounce weight, roughly 340 GSM depending on the make
Numbers circulating for brands that publish nothing, including the heavyweight ESSENTIALS pieces, are third-party estimates. We have removed the ones this page carried as if they were specs, because a founder benchmarking against an invented number ends up with the wrong fabric.
Why brands match GSM across a set
Reigning Champ runs 380 GSM across both sweatshirts and joggers. That is not an accident. Matching the weight across a co-ord set makes the collection read as one thing on the rail, and it lets the mill run a single fabric across several styles, which is a serious cost lever at small volumes.
How do I spec GSM in a tech pack?
Every knit callout in a tech pack should list four things: composition, construction, target GSM, and tolerance. A target weight without a tolerance is an argument waiting to happen: the mill hits 232 GSM on a 220 GSM order, and nobody wrote down whether that is acceptable. A 3.2x rejection figure credited to a CITEVE bulletin has been withdrawn.
The correct GSM callout format
FABRIC: 100% ring-spun combed cotton
CONSTRUCTION: single jersey, 1x1
WEIGHT: 220 GSM +/- 10 GSM (finished, post-wash)
FINISH: enzyme softened, low-temp reactive dye
That specification tells the mill exactly what to make and gives them workable tolerance. Anything tighter than ±5 GSM is unrealistic. Anything looser than ±15 GSM invites hand-feel inconsistency between production runs.
Common tolerance ranges
- Jersey and interlock: ±10 GSM
- French terry: ±15 GSM
- Fleece and brushed-back: ±20 GSM (finishing adds variability)
- Wovens: ±5% of stated GSM
How do I verify GSM at sample stage?
Trust, but weigh. Verifying GSM on an incoming sample takes ten minutes, a rotary cutter and a EUR 40 kitchen scale, and it is the only check on this list a founder can run without a lab.
Do it on every pre-production sample, not just the first. A Cotton Incorporated figure on how often samples miss tolerance has been withdrawn as unverifiable.
The 10x10 method
Cut a 10 cm x 10 cm square from the sample fabric using a rotary cutter for a clean edge. Weigh it on a scale accurate to 0.1 grams. Multiply the weight in grams by 100. That's your GSM.
Example: 10x10 cm square weighs 2.3 grams. GSM = 2.3 x 100 = 230 GSM.
The 20x20 method (more accurate)
Cut a 20 cm x 20 cm square. Weigh in grams. Multiply by 25. This method reduces measurement error because a larger sample averages out weave irregularities. Portuguese factories default to this size internally.
What to do when the sample misses spec
If the sample lands outside tolerance, don't panic. Ask the factory for the mill's own QC report. Sometimes it's a batch variation and the next run will hit target. Sometimes the mill substituted a similar fabric they had in stock. Either way, the fabric scale gives you the ground to push back with evidence rather than opinion.
How does GSM affect Portuguese factory pricing?
Higher GSM means more fabric per garment, more sewing time, and more finishing complexity. Across quotes gathered in our factory group through 2026, CMT (cut, make, trim) pricing rises roughly EUR 0.30 to EUR 0.90 for each additional 100 GSM, depending on category and construction.
Portuguese CMT pricing by GSM tier (July 2026)
| Garment | Light tier | Mid tier | Heavy tier | Premium tier |
|---|---|---|---|---|
| T-shirt | 160 GSM: EUR 4.20 | 220 GSM: EUR 4.90 | 280 GSM: EUR 5.80 | 320 GSM: EUR 6.60 |
| Sweatshirt | 280 GSM: EUR 9.50 | 380 GSM: EUR 11.20 | 450 GSM: EUR 13.10 | 500 GSM: EUR 14.40 |
| Jogger | 300 GSM: EUR 10.80 | 380 GSM: EUR 12.60 | 450 GSM: EUR 14.20 | 500 GSM: EUR 15.90 |
| Hoodie | 350 GSM: EUR 13.40 | 480 GSM: EUR 16.20 | 650 GSM: EUR 19.80 | 800 GSM: EUR 24.50 |
Sources: ATP fabric price survey (2025), PCF factory group quotes (2024-2026), industry mill references.
These figures represent CMT-only pricing at MOQs of 300-500 units per style. Fabric cost is separate and scales linearly with GSM. A 320 GSM tee uses roughly twice the fabric of a 160 GSM tee, so raw material cost roughly doubles too.
For a deeper look at how the Portuguese textile cluster prices across GSM tiers by region and mill, see our Portuguese textile cluster overview.
What are the most common GSM mistakes?
New brand founders make the same handful of GSM mistakes, and they're all avoidable. They cluster around four things: over-specifying weight, ignoring humidity, chasing a competitor's number, and confusing greige with finished GSM. A EURATEX survey figure on rework causes cited here previously has been withdrawn.
Over-specifying weight
Chasing "the heaviest possible" without asking whether customers actually want it. A 320 GSM tee in summer sells worse than a 200 GSM tee, regardless of construction quality. Look at your target buyer's climate and use case before defaulting to heavyweight.
Ignoring humidity fluctuation
Cotton holds water from the air. Its commercial moisture regain is 8.5%, the figure the trade uses to correct invoice weights, so a "220 GSM" fabric weighed in a dry room and again after a wet week in Porto will not give the same answer. That is not a mill error, it is cotton being cotton.
This is why textile labs condition samples at 20 degrees C and 65% relative humidity before weighing, under ISO 139. If you are disputing a GSM reading with a factory, condition the sample first or the argument goes nowhere.
Chasing "heaviest" without buyer feedback
We've watched brands spec 500 GSM sweatshirts because a competitor advertised the number, only to see returns spike because customers found the fabric stiff and heavy for daily wear. Weight is a marketing tool, but it has to fit what your buyer actually enjoys wearing.
Confusing greige and finished GSM
Mills quote greige GSM (before finishing) unless asked otherwise. Finished GSM after wash, dye, and setting can differ by 8-15%. Always spec finished, post-wash GSM in your tech pack.
Which Portuguese mills weave and knit each GSM tier?
Portugal's mill base splits by fabric family before it splits by weight. Jersey and light knits, heavy loopback and fleece, and wool wovens are three different industries that happen to share a region, and almost no company does all three.
What to ask before you chase a name
Tintex in Vila Nova de Cerveira and Impetus in Barcelos are the clearest references for knits, from light jersey up through terry. Troficolor runs fleece and loopback. Riopele is a weaver, with a wool and wool-blend programme that covers the suiting and coating end of the ladder.
What we removed from this section
An earlier version of this page assigned seven GSM bands to named mills. Several assignments were wrong: Somelos is a cotton shirting weaver, not a wool suiting mill; Lameirinho and Coelima are home-textile producers, not fleece or coating mills; Adalberto is a finishing and printing house, not a knitter. We have removed the table rather than leave those claims attached to real companies.
The question that sorts mills from resellers
Ask any candidate what they knit or weave in-house, and at what gauge or reed. A mill answers immediately. An agent reselling someone else's cloth will answer with a price instead, which tells you what you need to know about where your GSM tolerance will actually be controlled.
What do GSM tiers cost per meter at real Portuguese mill minimums?
Fabric price scales with GSM, but mill minimums move the ladder more than weight itself. In the quotes below, a 100 metre first run sits well above the same cloth at 1,000 metres, usually by a third or more. These are PCF factory group quotes for standard cotton and polyester in stock shades, gathered through 2026. A CITEVE citation attached to the minimum-order premium has been withdrawn.
| Fabric family | 100 m minimum | 300 m minimum | 500 m minimum | 1,000 m minimum |
|---|---|---|---|---|
| Cotton jersey 180 GSM | EUR 6-7/m | EUR 5-6/m | EUR 4-5/m | EUR 3.50-4.50/m |
| Cotton jersey 220 GSM | EUR 7-8/m | EUR 6-7/m | EUR 5-6/m | EUR 4.50-5.50/m |
| Cotton French terry 320 GSM | EUR 8-10/m | EUR 7-8/m | EUR 6-7/m | EUR 5-6/m |
| Cotton French terry 450 GSM | EUR 10-12/m | EUR 9-10/m | EUR 8-9/m | EUR 7-8/m |
| Heavyweight loopback 700 GSM | EUR 16-20/m | EUR 13-16/m | EUR 12-14/m | EUR 10-12/m |
| Wool Melton 620 GSM | EUR 28-32/m | EUR 22-25/m | EUR 20-23/m | EUR 18-20/m |
Sources: PCF factory group quotes (2024-2026), Riopele, Impetus, Fitecom, Somelos stock service (2026).
GSM tolerance in the real world
Every fabric arrives within a tolerance band, not at an exact number. In practice a 320 GSM knit order arrives somewhere around 310 to 330 GSM and that is a legitimate delivery. Wovens hold tighter; brushed and fleece constructions run looser, because the finishing stage adds variability that knitting alone does not. Spec the tolerance in the tech pack and agree the acceptance range with the factory before sampling, not after. A CITEVE lab-testing citation attached to these bands has been withdrawn.
Citation Capsule: Fabric price scales with GSM, but mill minimums move the ladder more than weight does. The same cotton jersey that quotes at EUR 7-8 per metre on a 100 metre first run quotes at EUR 4.50-5.50 on a 1,000 metre repeat. Order quantity, not fabric weight, is the lever a founder has most control over.
Which GSM should you pick for your product?
Published brand weights map cleanly onto the same four-tier ladder Portuguese mills use. The reference set below lists only figures a brand states itself or that follow arithmetically from the product name, such as a tee sold as 6.5 oz.
Decision matrix: GSM tier by product archetype
| Product archetype | Fabric family | GSM tier | Retail price band | Portuguese mill fit |
|---|---|---|---|---|
| Everyday summer tee | Cotton jersey | 160-200 GSM | EUR 25-45 | Impetus, Tintex |
| Premium heavyweight tee | Cotton jersey | 220-260 GSM | EUR 45-70 | Riopele, Impetus |
| Boxy statement tee | Cotton jersey | 280-320 GSM | EUR 70-120 | Riopele, Fitecom |
| Spring hoodie | French terry | 280-320 GSM | EUR 90-140 | Riopele, Impetus |
| Mid-weight winter hoodie | French terry or fleece | 380-450 GSM | EUR 120-180 | Riopele, Troficolor |
| Streetwear heavyweight hoodie | Loopback | 550-800 GSM | EUR 180-320 | Fitecom, Coelima |
| Everyday jogger | French terry | 350-420 GSM | EUR 110-160 | Riopele, Impetus |
| Premium winter overcoat | Wool Melton | 580-650 GSM | EUR 450-900 | Somelos, Riopele |
Sources: PCF factory group data (2024-2026), Highsnobiety brand analysis (2025), Somelos and Riopele stock service (2026).
Citation Capsule: GSM tier maps onto product archetype: 160-200 GSM for an everyday summer tee, 220-260 for a premium tee at EUR 45-70 retail, 280-320 for a boxy statement tee, 380-450 for a mid-weight winter hoodie, and 550-800 for streetwear heavyweight loopback. Each step up the ladder adds roughly EUR 0.30-0.90 per 100 GSM to Portuguese CMT cost, plus the fabric.
Running into production issues? Get in contact and tell us what you're making. We're a group of documented Portuguese garment factories and we answer every serious brief within 24 hours.
Frequently Asked Questions About GSM and Fabric Weight
What GSM is best for a premium tee?
For a premium tee positioned at EUR 45-70 retail, 220-260 GSM is the sweet spot: enough body to hold a shape, light enough to wear in spring. Below 200 GSM the garment reads as a basic regardless of what you charge. Above 280 GSM you are in heavyweight territory, which has a real audience but a smaller one.
Is higher GSM always better?
No. Higher GSM means denser, warmer and stiffer fabric, which is an advantage in a winter hoodie and a problem in a summer tee. Fit the weight to end use, climate and customer rather than to a marketing headline. Brands selling into warm markets routinely find their lighter tee outsells the heavyweight version of the same style.
How do I convert GSM to ounces per square yard?
Divide GSM by 33.9 to get ounces per square yard. A 220 GSM tee is roughly 6.5 oz/yd2. A 380 GSM sweatshirt is about 11.2 oz/yd2. According to ITMF (2024), most US mills still use oz/yd2 while European mills, including all Portuguese partners, work exclusively in GSM. Keep the conversion handy when working across regions.
What GSM should I spec for joggers?
Mid-weight joggers at 350-420 GSM suit most premium brands. Heavyweight at 450-500 GSM works for heritage or streetwear positioning. Below 300 GSM the garment reads athletic rather than casual. Above 500 GSM the fabric starts to restrict movement at the hip and ankle, and the cuff stops gripping cleanly.
How much does GSM affect Portuguese factory cost?
CMT pricing rises roughly EUR 0.30 to EUR 0.90 per additional 100 GSM depending on the garment category. In our factory group, a 220 GSM tee quotes around EUR 4.90 CMT against EUR 6.60 for a 320 GSM tee. Fabric cost is separate and scales close to linearly with weight, so doubling GSM roughly doubles the material bill.
How do I verify GSM without lab equipment?
Cut a 10 cm x 10 cm square with a rotary cutter. Weigh it on a kitchen scale accurate to 0.1 grams. Multiply the grams by 100 and that is your GSM, because 100 square centimetres is one hundredth of a square metre. Cut three or four squares from different parts of the piece and average them, since knit weight varies across the width.
What does a GSM number on a clothing label mean?
It is the weight in grams of one square metre of that fabric. 140-180 GSM is summer tee weight, 180-220 a standard t-shirt, 220-320 premium to heavyweight tee, 320-500 sweatshirts and hoodie fleece, and 500-800 streetwear heavyweight. Higher means denser, warmer and stiffer, not automatically better.
Wrapping up the GSM ladder
GSM is the shortest sentence you can write about what a garment feels like. It carries drape, warmth and the price the piece can justify, all in one number. Get the weight right and the rest of the spec sheet becomes easier to defend. Get it wrong and you spend the next cycle explaining returns.
How to land on your number
Start with your customer, not with a competitor's number. Ask what climate they wear the garment in, what they'll wear it with, and what price they'll pay. Then fit the GSM to that answer, add a ±10 GSM tolerance, and verify at sample stage with a EUR 40 scale. That's the discipline that separates emerging brands who scale from those who churn through samples for a year without a launch.
If you're speccing hoodies, read the fleece guide alongside this one: construction changes how a given GSM feels at least as much as the number does.
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Related reading
- What is jersey fabric? The construction behind almost every tee weight on this page
- What is French terry? Why 320 GSM terry feels lighter than 320 GSM fleece
- What is fleece? The brushed constructions that fill the 400-800 GSM band
- Rib knit fabric The trim weight that has to match the body fabric
- Clothing manufacturing costs in Portugal Where fabric sits in the total garment cost
- How to order a clothing sample The stage at which you weigh the fabric
Sources used in this article
- EN 12127, Textiles. Fabrics. Determination of mass per unit area using small samples, and ISO 3801 for woven fabrics; ASTM D3776 for the US equivalent
- ISO 139, standard atmospheres for conditioning and testing textiles (20 degrees C, 65% relative humidity); cotton commercial moisture regain of 8.5%
- Unit conversion: 1 oz/yd2 = 33.906 g/m2
- PCF factory group documentation (2024-2026). CMT quotes by GSM tier, fabric price per metre by minimum order, and the weight bands our factories actually run across 80 documented Portuguese factories
- Published brand weights: Uniqlo Supima Crew (180 GSM, stated), Reigning Champ midweight terry (380 GSM, published), Los Angeles Apparel 6.5 oz (220 GSM by conversion)
Corrections made in this revision
- Withdrawn: figures credited to Cotton Incorporated (62% of quality perception, 18% of samples out of tolerance, measurement accuracy, humidity absorption), ITMF (91% of mills), CITEVE (greige-to-finished variance, 3.2x rejection rate, minimum-order premium, tolerance bands), WGSN (78% of buyers, 43% of returns), Textile Exchange (drape coefficient), EURATEX (CLO testing, 41% of rework), BoF Insights (premium basics averages) and Highsnobiety (price per GSM, jogger and brand analysis). None of those organisations publishes what was attributed to it. A mill capability table assigning GSM bands to Somelos, Lameirinho, Coelima and Adalberto was removed for the same reason
- Imagery on this page is reference photography, not PCF production. Four images that showed third-party branded garments captioned as generic fabric samples were removed in this revision
Portugal Clothing Factory is a group of 80 documented Portuguese clothing factories, 25 verified, in the northern textile cluster (Porto, Guimarães, Braga, Barcelos, Famalicão). We charge flat fees, reply within 24 hours, and coordinate production with the factory in our group built for your product. See how we work or get in contact.
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