What is GSM in Fabric, and Why Does it Matter?

By ShirtSpace | Nov 07, 2024 |  Updated Nov 15, 2024

If you have been dipping your toes in the pool of blank apparel, you might have seen the acronym “GSM” listed on product descriptions and when apparel is discussed. So, what is GSM fabric exactly? Well, you aren’t the first to ask this question. Read on to learn more about GSM and why it is important for fabric feel and garment decorating. 

Hero image credit: SashkaB

What is GSM in Fabric?

The acronym GSM can stand for many things – global systems for mobile, general sales manager, or even graphic screen mesh. But what exactly is GSM in textile products? GSM stands for “grams per square meter.” All types of materials have a GSM. This measurement is commonly used in the apparel and fabrics industries, indicating weight and density. 

Fabric GSM Definition

When breaking down GSM in textile industries, Silver Bobbins defines fabric GSM as follows:

“The GSM of fabric stands for grams per square meter, a unit of measurement that describes the weight and density of a piece of material. This unit of measurement is commonly used on certain types of fabric, like cotton. It is also used to describe fabric items like bedsheets, bath towels, and blankets.”

Shirt pictured: Alternative Apparel AA1973 Eco-Jersey™ Crew T-Shirt in “Eco Gray” with a GSM of 145, which is a standard GSM.

How is GSM Measured in Fabric?

GSM is expressed in grams per square meter (g/m²). A GSM measurement is determined by calculating the fabric weight within one square meter area.  A small swatch is taken from the material, typically 10 cm x 10 cm, and the sample is weighed on a precision scale to ensure accuracy. You would then plug the weight into this formula:

GSM = sample piece weight (in grams) x 10,000 / area of fabric sample in square meters

So, for example, if our sample weight was 10 grams, the GSM would be 100:

• EXAMPLE: 1,000 GSM = 10 grams x 10,000 / 10 cm x 10 cm
   

This gives an idea of not only fabric weight but also density. Why is density critical, outside what you can determine about a garment based solely on its weight? The answer is that a tightly packed weave provides a smoother face and optimized printing experience. Additionally, embroiderers will need to know the GSM to determine the proper needle to use for the best results. You can use the equation to find an accurate GSM, but you can also use a GSM measurement calculator to quickly find a fabric’s GSM. 

Why Does GSM Matter for Fabric Quality?

Now that we know the GSM meaning: fabric weight and density – we can discuss the reasons why this matters.

Although it is not the main criterion for assessing a garment’s quality, GSM is a key factor because it influences the fabric's feel, durability, and performance for specific uses. A higher GSM typically signifies a denser, more durable fabric that can withstand wear and tear, making it ideal for products that require resilience, like outerwear or upholstery. 

In contrast, lower GSM fabrics, which are lighter and thinner, may prioritize breathability and comfort over durability, fitting well for summer apparel or delicate garments. By understanding GSM, one can gauge not only how substantial a fabric feels, but also its quality and how well it will hold up over time in various applications.

When it comes to decorating methods such as a printing (HTV, DTF/DTG, sublimation and screen printing), high GSM garments typically take less ink to print on, and result in more vivid details and vibrant colors. This is because the dense and smooth surface will support a layer of ink better. Low GSM fabrics have tiny holes within the weave of the fabric, which can absorb the ink, and make for a less smooth printing surface, and in turn, a less smooth print. Embroiderers prefer high GSM and heavyweight fabrics, too, since they are so durable and strong.

Sweatshirt pictured: Bella+Canvas B7502 Ladies' Cropped Fleece Hoodie in “Atlantic”, which a GSM of 230, which makes it a lightweight sweatshirt.

GSM Chart for Common Fabric Types

Consult this fabric GSM chart to decide which t-shirt and sweatshirt GSM ranges are suitable for your needs. 

How to Choose the Right Fabric GSM for Your Next Project

Choosing the right GSM for the apparel decorating method you want to carry out is essential for best results. Find your favorite method and let it guide you in finding the perfect apparel GSM:

Bleaching: Heavier fabrics tend to hold up to the harsh chemicals used in bleaching and reverse tie-dye, such as color removers, typical bleach and hydrogen peroxide. Bleach can be harsh on lightweight (and low GSM) fabrics, sometimes burning holes in the material. Hydrogen peroxide sometimes helps stop the chemical process in its tracks. So, if you feel that you have reached your desired lightness level, you can apply it to the garment to halt any unwanted damage. 

Embroidery: Embroiderers love a good heavyweight t-shirt or sweatshirt. This is because the fabric holds up the design well and is easier to stitch into. The more stable, the better, when embroidering. 

HTV: Higher GSM fabrics can help with the proper adhesion of heat transfer vinyl. Additionally, heavier-weighted apparel typically can handle heat application more easily than a lightweight fabric. The vinyl will look fresh and new longer on a higher GSM (and weight) than on a light GSM tee. Lightweight fabrics might snag, stretch or warp in unwanted ways and almost always require an additional stabilizer to prevent puckering or bunching up. 

DTF/DTG: 

• Direct-to-Film Printing: Since DTF printing involves transferring ink from a film onto the fabric using heat, a higher GSM fabric can be beneficial. Thicker fabrics are more stable, helping the transfer process to adhere better without warping or shifting. They also provide a smoother surface for the transfer, ensuring sharp and crisp designs. Lower GSM fabrics, being thinner and more delicate, may require extra care to avoid overheating or damage during the transfer process.
• Direct-to-Garment Printing: For DTG printing, GSM affects how the fabric takes the ink. Higher GSM fabrics are thicker, which can allow for more controlled ink absorption and prevent the ink from penetrating through the fabric. Thicker fabrics often produce more vibrant and longer-lasting prints, as the ink stays on the surface. Thinner fabrics with lower GSM, may absorb ink more rapidly, potentially resulting in a less vibrant print or causing uneven color distribution, or dye migration, especially if the fabric is too soft or flimsy to hold the ink properly.

Fabric Painting: A high GSM fabric is very useful for fabric painting, especially if you are painting with a standard brush. Airbrush painting is a little easier to apply to lightweight fabrics, but it’s helpful to have a steady surface to apply the ink. Denser, heavier fabrics will allow just that!

Screen Printing: Ink bleeding and uneven prints are a woe of the past with high GSM fabics. With a thick, dense canvas, screen prints will adhere well to the fabric surface, and you won’t have to worry about ink soaking through the fabric. GSM also aids in the longevity of the screen print, making it a longer-lasting piece of clothing that is more resilient to wear and tear over time. 

Sublimation Printing: For sublimation printing, having light-colored 100% polyester or polyester-heavy apparel is the most important part. You typically want to aim for 60-65% polyester. A high GSM count is not necessary for sublimation, but can help the opaqueness of the design, avoiding a sheer-looking print. 

Tie-Dye: You can tie-dye any GSM of fabric, although some tie-dyers report that they prefer mid to heavyweight tees, since it can be easier to fold the material. For sweatshirts, the material’s makeup and fabric color is more important than the GSM. The GSM will be a personal preference. You will want to select a 100% cotton or cotton-heavy fabric for a dye-worthy sweatshirt.

Shirt pictured: Shaka Wear SHGD Garment-Dyed Crewneck T-Shirt in “Mustard” with a GSM of 230, making it an exceptionally heavyweight tee. 

Now That You Are a GSM Pro

Now that you know what is GSM in fabric, and how this ties in with your blank apparel product selections, we are curious to hear what GSM you like. Whether it be for your preferred decorating method or just the overall fit and feel. We also ask that you share in the comments if you have a favorite apparel item with a notable GSM. All apparel is great, but we are suckers for a nice, high GSM! 
 

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