What Is GSM in Fabric? Fabric Weight Explained

GSM is the weight of one square metre of fabric in grams. Here is what the common ranges mean for T-shirts, hoodies, activewear, denim and towels, how to convert GSM to ounces, and how to specify fabric weight when you brief a manufacturer.

What GSM Means in Fabric

GSM stands for grams per square metre. It is the weight of one square metre of a fabric, measured in grams, and it is the standard way factories outside the United States describe how heavy a fabric is. A single jersey listed at 180 GSM weighs 180 grams per square metre; a fleece listed at 320 GSM weighs 320 grams for the same area.

That single number tells you a lot before you have touched a swatch. Higher GSM means more fibre in every square metre, so the fabric is usually thicker, more opaque, warmer and more durable, and it costs more to produce and to ship. Lower GSM means a lighter, cooler, more breathable fabric that drapes more and dries faster. Neither end is better. The right weight depends on what the product is for.

This guide explains how GSM works, the weight ranges commonly used for T-shirts, hoodies, activewear, shirting, denim and towels, how to convert GSM to ounces, why GSM on its own does not tell you quality, and how to specify fabric weight when you brief a manufacturer. It is written for private label and DTC brands ordering a first or early production run, whether from a factory you found yourself or through a sourcing partner such as SourceBridge, which works with clothing and home-textile manufacturers in Turkey.

Why Fabric Weight Matters When You Order Production

For a consumer, GSM is a way to compare two products online. For a brand placing a production order, it is a binding part of the specification, and it affects four things at once.

How the product feels and performs. Weight drives thickness, opacity, warmth, stretch recovery, drape and drying time. A T-shirt that is 30 GSM lighter than the reference you approved will feel noticeably thinner, and customers notice.

Unit price. More fabric weight means more yarn per garment. Weight is one of the main levers in a fabric quote, alongside fibre, yarn quality, construction, dyeing and finishing.

Shipping weight and landed cost. A heavier hoodie or bath towel weighs more in the carton, which shows up in freight and, for Amazon sellers, in fulfilment fees. The landed cost calculator is a quick way to see how unit weight moves the total.

Whether your sample matches production. If the approved sample was 220 GSM and the bulk order arrives at 195, the product is not the one you approved. A written GSM target with a tolerance is what lets you check that.

How GSM Is Measured

The usual method is simple. A circular cutter cuts a sample of exactly 100 square centimetres from the fabric, the sample is weighed on a precision scale, and the weight in grams is multiplied by 100 to give grams per square metre. A 2.2 gram circle is a 220 GSM fabric.

Two details matter more than the arithmetic.

Before or after washing. Knits in particular can shrink and compact when they are washed, which can push the measured GSM up. Ask whether a quoted weight is the greige (unfinished) weight or the finished weight after dyeing and finishing, and specify finished weight in your order.

Tolerance. No fabric comes off the line at exactly the same weight in every roll. Agree a tolerance in writing, for example plus or minus 5 percent, so that both sides know when a deviation is acceptable and when it is a defect.

You can check this yourself. A GSM cutter and a jewellery scale are inexpensive, and weighing a swatch from your approved sample and from the production order is one of the most useful checks a small brand can make.

How to Convert GSM to Ounces

Most of the world quotes fabric weight in GSM. Many US brands, blank suppliers and denim mills quote it in ounces per square yard. The conversion is fixed:

GSM to oz per square yard: divide by 33.906. A 180 GSM jersey is about 5.3 oz.

oz per square yard to GSM: multiply by 33.906. A 14 oz denim is about 475 GSM.

A few reference points, rounded:

150 GSM is about 4.4 oz per square yard

180 GSM is about 5.3 oz

200 GSM is about 5.9 oz

250 GSM is about 7.4 oz

300 GSM is about 8.8 oz

400 GSM is about 11.8 oz

One trap: some suppliers quote ounces per linear yard rather than per square yard. A linear yard is a yard of fabric at whatever width the roll happens to be, so the number changes with the width and is not comparable with GSM. When you see an ounce figure, ask which one it is.

Common GSM Ranges by Product

The ranges below are typical starting points used across the industry, not standards. The same weight can feel very different in a different fibre or construction, so use them to frame a conversation with a manufacturer and confirm against a physical reference.

T-shirts

Lightweight, roughly 120 to 160 GSM: fashion tees, layering pieces, summer styles. Softer drape, more see-through in light colours.

Midweight, roughly 160 to 200 GSM: the everyday range for most basic and promotional tees.

Heavyweight, roughly 200 GSM and above: structured, boxy and streetwear tees. Many heavyweight styles sit well above 220 GSM.

On the question of 180 GSM versus 200 GSM, neither is better in the abstract. The 200 will feel a little more substantial and hold its shape slightly better; the 180 will be a little lighter and cooler. If your customer expects a thicker tee, go heavier; if they wear it in hot weather or under other layers, go lighter.

Sweatshirts and hoodies

French terry, roughly 250 to 350 GSM: looped back, lighter, a year-round weight.

Brushed fleece, roughly 280 to 400 GSM and above: brushed inside for warmth. Heavyweight streetwear hoodies are often specified at the top of this range or beyond it.

A 400 GSM hoodie is heavy. It feels dense and warm, holds its shape, and costs more in fabric and freight than a 300 GSM one.

Activewear and leggings

Performance knits with elastane are often specified in a range of roughly 180 to 300 GSM. Weight here is closely tied to opacity and compression: a legging that is too light can turn see-through when stretched, which is one of the most common activewear complaints. Specify weight and composition together, and test the sample stretched, not flat.

Woven shirting and dresses

Woven shirting fabrics such as poplin and oxford are usually far lighter than knits, commonly in the range of about 100 to 150 GSM. Woven weight affects crispness and transparency more than warmth.

Denim

Denim is almost always quoted in ounces. Lightweight denim for shirts and summer styles sits below about 12 oz; midweight jeans are commonly around 12 to 14 oz; heavyweight denim runs above that. In GSM, 12 oz is about 405 and 14 oz about 475.

Towels

For towels, GSM is the main quality metric buyers compare, and the bands are well established. The ranges SourceBridge uses in its private label towel guide are:

300 to 400 GSM: lightweight and quick-drying. Gym, beach and travel towels.

450 to 550 GSM: mid-weight. The most common range for everyday bath towels.

600 to 700 GSM: hotel weight. Thick and plush.

700 GSM and above: very heavy and soft, and slower to dry.

Heavier is not automatically better for a towel. A 700 GSM towel takes longer to dry and costs more to ship; a flat-woven Turkish peshtemal is light by design. Choose the band for the use, then specify the cotton and construction.

Why GSM Alone Does Not Tell You Quality

GSM measures weight, not quality. Two fabrics at the same GSM can behave very differently because of everything else in the specification:

Fibre and yarn. Combed or ring-spun cotton, carded cotton, long-staple cotton, polyester and blends all perform differently at the same weight. A heavy fabric made from a coarse, short-staple yarn can pill and feel rough.

Construction. Single jersey, interlock, piqué, rib, French terry and fleece have different thickness, stretch and recovery at the same GSM.

Finishing. Enzyme washing, brushing, peaching, compacting and garment dyeing all change hand feel, and some change weight.

Shrinkage and stability. A fabric that meets its weight but shrinks badly after the first wash is still a defect.

This is why a factory needs more than a number. "Heavyweight cotton" is not a fabric specification. "100% combed cotton single jersey, 220 GSM finished, enzyme washed, shrinkage within agreed limits" is.

How to Specify Fabric Weight When You Brief a Manufacturer

Fabric weight belongs in the fabric section of your tech pack, next to composition and construction. A complete fabric line includes:

Composition, for example 100% cotton or 95% cotton and 5% elastane.

Construction, for example single jersey, French terry, brushed fleece or poplin.

Finished GSM and the tolerance you will accept.

Finish, such as enzyme wash, brushing or a garment dye.

Any certification you need, such as OEKO-TEX or GOTS.

A physical reference if you have one: a garment or swatch whose weight and hand you want to match.

If you do not yet know the weight you want, that is normal for a first product. Send the manufacturer a garment you like and ask them to weigh it and propose a fabric, or ask for swatches at two or three weights and choose by hand feel. Then put the chosen figure in writing before sampling starts.

Checking GSM at Sampling and in Production

GSM is easy to check, so check it at each stage rather than trusting the label.

At sampling: weigh a swatch from the approved sample and record it against the specification. With Turkish manufacturers a sample typically takes 7 to 14 days to make and 5 to 7 days by courier, and 2 to 3 rounds are normal for a new style, so this is the point to correct the weight, not after bulk production.

Before bulk cutting: ask for a fabric approval from the production lot, including its measured weight.

At pre-shipment inspection: include a GSM check from several cartons in the inspection, measured against the same tolerance.

SourceBridge works with clothing and home-textile manufacturers in Turkey, including the towel producers of Denizli. Custom fabric compositions and GSM are part of the textile sourcing brief, apparel MOQs start from 300 units per style, and samples are approved before production. If you are still deciding how a first order should be structured, the guide to clothing manufacturers for startups covers MOQ and sampling in more detail.

FAQ: GSM and Fabric Weight

What does GSM mean in clothing?

GSM means grams per square metre: the weight of one square metre of the fabric a garment is made from. In clothing it is used to describe how heavy, thick and substantial a fabric is. A 160 GSM T-shirt is a light-to-midweight tee; a 350 GSM hoodie is a heavy one.

What is a good GSM for fabric?

It depends on the product. As rough starting points, everyday T-shirts are commonly around 160 to 200 GSM, heavyweight tees above 200, hoodies and sweatshirts around 250 to 400, and everyday bath towels 450 to 550. A good GSM is the one that suits the use, the season and the price point of your product, confirmed against a physical sample.

Is 300 GSM fabric thick?

For a T-shirt, yes: 300 GSM is far heavier than a typical tee. For a sweatshirt or French terry hoodie, 300 GSM is a common mid-range weight. For a bath towel, 300 GSM is light. Whether 300 GSM is thick depends entirely on the product it is used for.

Is 400 GSM heavy?

For apparel, yes. A 400 GSM fleece hoodie is dense, warm and structured, and is often marketed as heavyweight. For towels, 400 GSM is at the lighter end, typical of gym, beach and travel towels.

Which is better, 180 GSM or 200 GSM?

Neither is better in general. A 200 GSM T-shirt feels slightly more substantial and holds its shape a little better; a 180 GSM one is slightly lighter and cooler. Choose based on how your customer wears the product, then specify the weight and a tolerance so the production order matches the sample.

What is a good GSM for towels?

Everyday bath towels most commonly sit around 450 to 550 GSM. Hotel-weight towels are around 600 to 700 GSM, and lightweight gym, beach and travel towels around 300 to 400 GSM. Heavier towels feel plusher but take longer to dry and cost more to ship.

Does a higher GSM mean better quality?

No. GSM measures weight, not quality. Fibre, yarn, construction and finishing determine how a fabric feels, wears and washes. A lighter fabric made from a good yarn can outperform a heavier one made from a coarse yarn. Use GSM together with the rest of the fabric specification.

How do I convert GSM to oz?

Divide GSM by 33.906 to get ounces per square yard, or multiply ounces per square yard by 33.906 to get GSM. For example, 180 GSM is about 5.3 oz and 300 GSM about 8.8 oz. Check whether an ounce figure is per square yard or per linear yard, because the two are not comparable.

What Is GSM in Fabric? Fabric Weight Explained for Clothing and Towels