A print on demand catalog will throw a lot of numbers at you: 4.2 oz, 5.3 oz, 180 GSM, 32 singles, combed, ring spun. Most of it gets skimmed past because it reads like packaging filler. It isn't. Those specs tell you, before you ever touch the shirt, how it's going to feel, how it's going to print, and what kind of brand it's going to look like on a customer's back.
The short answer
GSM (grams per square meter) and oz/yd² (ounces per square yard) both measure fabric weight, just in different units; ring spun and combed describe how the cotton yarn was processed, not how heavy the fabric is; and singles count measures yarn fineness, not fabric weight either. A heavier shirt isn't automatically a better one, and a higher singles count isn't automatically a heavier shirt. They're separate specs that combine to produce the final hand feel.
For most print on demand sellers building a modern, fitted storefront, choose a lighter combed ring spun cotton tee in the 4.0 to 4.5 oz/yd² range, like the Bella Canvas 3001 or Next Level 3600; pick a heavier tee at 5.3 oz/yd² or above, like the Gildan 5000 or Comfort Colors 1717, instead when you want a sturdier, boxier, or more vintage feel. Neither direction is wrong. They're different fabric decisions aimed at different looks.
What does GSM mean on a t-shirt spec sheet?
GSM means grams per square meter, a straightforward measure of how much fabric weighs for a given area, independent of how that fabric is cut into a finished shirt. It's the metric-system counterpart to ounces per square yard (oz/yd²), which is what most US print on demand catalogs actually print on their spec sheets. A lightweight tee sits around 135 to 150 GSM. A heavyweight tee runs 180 GSM or more.
GSM vs. oz/yd²: do they measure the same thing?
Yes, they measure the exact same property of the fabric, just in different units, and you can convert cleanly between them. The standard conversion factor is 1 oz/yd² = roughly 33.9 GSM. So the Bella Canvas 3001's 4.2 oz/yd² works out to about 142 GSM, and the Gildan 5000's 5.3 oz/yd² comes out to about 180 GSM, which matches the 180 G/SqM figure Gildan's own spec sheet lists for that shirt. If a supplier only gives you one unit, you don't need to guess: multiply oz/yd² by 33.9 to get GSM, or divide GSM by 33.9 to get oz/yd².
What does ring spun cotton mean, and why do POD sellers care?
Ring spun cotton is made by continuously twisting and thinning cotton fibers in a spinning process that produces a finer, stronger, smoother yarn than cheaper alternatives. The twisting locks the fibers together tightly, which is why ring spun fabric resists pilling and holds its shape through repeated washing better than a coarser yarn does. For a print on demand seller, this matters because it's the baseline quality signal on most premium blanks: the Bella Canvas 3001, the Next Level 3600, and the Gildan Softstyle 64000 are all ring spun, and it's one of the first specs worth checking on any new blank you're considering.
What is open end cotton?
Open end cotton is spun on a high-speed rotor instead of the slower ring spinning process, using shorter fibers to produce yarn faster and more cheaply. That speed comes at a cost: open end yarn is thicker, coarser, and less tightly bound than ring spun yarn, which generally means a rougher hand feel and a fabric that wears and stiffens faster over time. Not every blank discloses its spinning method. Gildan's spec sheet for the 5000 Heavy Cotton tee, for example, lists it as 100% cotton at 20 singles without a ring spun or combed claim either way, so don't assume a shirt is ring spun just because the listing calls it "100% cotton."
What does combed cotton mean?
Combed cotton has gone through an extra mechanical step, after carding but before spinning, that removes short, weak fibers and leftover impurities so only the longer, more uniform fibers remain. That extra step costs more, but it produces a smoother, stronger, more consistent yarn than uncombed (carded) cotton. The Bella Canvas 3001 markets its fabric as "Airlume combed and ring spun cotton," and the Next Level 3600 uses combed ring spun cotton as well, which is a real part of why both feel noticeably softer than a shirt that's only ring spun without also being combed, like the Gildan Softstyle 64000.
What does "32 singles" or "20 singles" actually measure?
Singles count measures how fine an individual strand of spun yarn is, similar in concept to thread count on bedsheets: the higher the number, the finer and thinner the single strand. A cheap, basic tee is commonly spun at 18 to 20 singles, while a premium soft-hand tee is usually spun at 30 singles or finer. The Gildan 5000 is spun at 20 singles, the Gildan Softstyle 64000 at 30 singles, and the Bella Canvas 3001 and Next Level 3600 at a finer 32 singles, which tracks directly with how each of those shirts actually feels in hand.
Does a higher singles count always mean a heavier or better shirt?
No, and this is where a lot of sellers misread a spec sheet. Singles count is about yarn fineness, not fabric weight, and the two don't move together in a fixed way. The Gildan Softstyle 64000 is 30 singles at 4.5 oz/yd², while the Bella Canvas 3001 is a finer 32 singles at a lighter 4.2 oz/yd². A finer single can still be knit into a denser fabric, so you can't infer a shirt's weight from its singles count alone, and you can't assume a higher singles number automatically makes one shirt objectively better than another. It tells you about yarn fineness and likely softness, nothing more.
What fabric weight is best for print on demand t-shirts?
There's no universal answer, because weight is a style decision as much as a quality one. Lightweight tees in the 4.0 to 4.5 oz/yd² range, roughly 135 to 150 GSM, like the Bella Canvas 3001 and Next Level 3600, drape closer to the fitted retail tees sold by current direct-to-consumer apparel brands. Heavier tees at 5.3 oz/yd² and up, 180 GSM or more, like the Gildan 5000 and the garment dyed Comfort Colors 1717 at 6.1 oz/yd² (about 207 GSM), read as sturdier, boxier, or more vintage, which is exactly the look some brands are going for on purpose. Pick the weight that matches the silhouette your listing photos are promising, not whichever number sounds more premium on paper.
How does fabric weight and cotton quality affect DTG print quality?
Finer, combed yarn gives DTG ink a smoother, more even surface to sit on, which tends to produce crisper small text and fine linework than a coarser, uncombed yarn does. Heavier, coarser fabrics like the Comfort Colors 1717 have more visible fabric texture, which suits bold graphics and larger type well but will soften the crispest edges of very fine detail compared to a smoother, combed surface like the Bella Canvas 3001's. Neither direction is a defect. A heavier, coarser tee and a lighter, smoother tee are simply better suited to different kinds of artwork, and it's worth matching your design's detail level to the blank's surface rather than assuming every blank will render a design identically.
Common print on demand blanks by weight and cotton quality
| Blank | Weight (oz/yd²) | Approx. GSM | Cotton type | Singles |
|---|---|---|---|---|
| Bella Canvas 3001 | 4.2 oz | ~142 GSM | Airlume combed, ring spun | 32 |
| Next Level 3600 | 4.3 oz | ~146 GSM | Combed, ring spun | 32 |
| Bella Canvas 3501 (long sleeve) | 4.2 oz | ~142 GSM | Airlume combed, ring spun | 32 |
| Gildan Softstyle 64000 | 4.5 oz | ~153 GSM | Ring spun (not marketed as combed) | 30 |
| Gildan 5000 | 5.3 oz | ~180 GSM | 100% cotton (spinning method not disclosed) | 20 |
| Comfort Colors 1717 | 6.1 oz | ~207 GSM | Ring spun (not marketed as combed), garment dyed | Not disclosed |
| Comfort Colors 6014 (long sleeve) | 6.1 oz | ~207 GSM | Ring spun, garment dyed | Not disclosed |
| Gildan 18500 (hoodie) | 8 oz | ~271 GSM | Cotton/poly blend fleece | Not disclosed |
| Independent Trading IND4000 (hoodie) | 10 oz | ~339 GSM | Ring spun cotton/poly blend fleece | 32 (face yarn) |
GSM figures above are calculated from each manufacturer's listed oz/yd² using the standard 33.9 conversion factor and rounded to the nearest whole number. Spinning method and singles count are left as "not disclosed" where the manufacturer's own spec sheet doesn't state one, rather than guessed.
Which should you choose?
Choose a lighter, combed ring spun tee (4.0 to 4.5 oz/yd²) when:
- You're building a fitted, modern retail look
- Softness and hand feel are a selling point
- Your designs include fine detail or small text
Choose a heavier tee (5.3 oz/yd² or more) when:
- You want a sturdier, boxier, or more substantial garment
- Your brand leans vintage, streetwear, or garment dyed
- Your artwork is bold and simple rather than fine detail
Watch for singles count and combed/ring spun claims independently of weight. A shirt can be heavy and coarse, heavy and fine, light and coarse, or light and fine. Reading all three specs together, not just the oz number, is what actually tells you how a blank is going to feel and print.
Fabric weight also changes how a shirt drapes and folds, which is part of why a mockup built on the actual blank you sell looks different from a generic flat template. Drop Studio generates mockups on the real weight and fit of each blank, so a heavyweight boxy tee folds like a heavyweight boxy tee and a lightweight fitted tee drapes like one.
Related reading:
- Gildan 5000 vs. Bella Canvas 3001: Which T-Shirt Should You Sell?
- Bella Canvas 3001 vs. Next Level 3600
- Comfort Colors 1717 vs. Bella Canvas 3001: Which Should You Sell?
Sources: Canvas Etc, Oz to GSM Converter (NIST factor); manufacturer spec sheets for the Gildan 5000 and Bella Canvas 3001; Rush Order Tees, What Is Ring Spun Cotton. GSM figures are calculated conversions, not independently measured. Specs vary by provider and season, always confirm current numbers with your print provider before listing.