GSM Explained for Bulk T-Shirts
By The Velocity Wear Team
GSM is grams per square metre: the weight of the fabric, measured by area rather than by garment. Our t-shirts run 150 to 240 GSM in combed ring-spun cotton. Lower numbers breathe and drape, higher numbers hold shape and hide what is underneath. It is a useful shorthand for density, but it says nothing about how the yarn was spun or the shirt sewn.
What is GSM actually measuring?
Cut a square metre of the fabric and weigh it. That is the number. Because it is measured by area, a size small and a size triple extra large in the same fabric share the same GSM even though one weighs far more on the scales. This is why GSM, rather than garment weight, is the figure on a spec sheet: it lets you compare two fabrics without worrying about which size was weighed.
Density is not thickness, either. A tightly knitted fine yarn can be denser and thinner than a loosely knitted coarse one. What the number reliably predicts is opacity, drape and how much fibre there is to take wear. What it does not predict is softness, which comes from the yarn and the finishing. The related terms you will meet on a quote are defined in our glossary.
What does each weight feel like?
At 150 to 165 GSM you have a light shirt that moves with the body, dries quickly and packs small. It suits hot weather, high-volume giveaways and anything shipped a long way. Held to a window it will show some light through, so choose a mid or dark tone unless you are content with that.
At 180 to 200 GSM you are in the range most people think of as a normal good t-shirt. It is opaque in white, it hangs straight rather than clinging, and it survives regular washing without the hem curling. For staff kit, society shirts, event crew and most retail, this is the default and it is the default for a reason.
At 220 to 240 GSM the shirt has presence. It stands away from the body, the shoulder seam holds a line, and colours read deeper because there is more fibre carrying dye. It is the weight for anything sold rather than given away, and for boxy or oversized cuts that need structure. The cost is warmth and drying time. The head-to-head is in midweight vs heavyweight on t-shirts.
Does GSM change what you pay?
It moves the number, because heavier fabric uses more cotton and costs more to ship, but it moves it less than buyers expect. T-shirts start from $13 a piece at our 50-piece minimum, and within the 150 to 240 range the fabric step is smaller than the step between a one-colour print and a three-colour one. Quantity is what really moves the price: the tiers run 50 to 99, 100 to 249, 250 to 499, 500 to 999 and 1,000 plus, reaching up to 35% off the 50-piece rate. From-prices are on the wholesale t-shirts page.
Does the print sit differently on a heavier body?
Slightly, and it is worth knowing before you approve artwork. A denser fabric has a flatter, more closed surface, so ink sits more on top and a fine line holds its edge well. A lighter fabric absorbs more, which softens an edge marginally but makes a large solid block feel less stiff on the shirt. If your design is a big solid graphic, a heavier body will carry it more comfortably. If it is fine type, either works and the heavier one holds a touch more detail.
Whichever weight you pick, the wash instruction should match it. Heavier cotton takes longer to dry and is more often tumbled, which is exactly the condition that shortens a print's life. We cover that in care and washing for t-shirts.
