Choosing fabric and GSM for custom T-shirts and hoodies
Fabric is most of what a customer feels when they pick up your T-shirt or hoodie. This guide explains GSM, the common knit fabrics, and how to specify what you want so the sample — and the bulk — match your idea.
Updated · 4 min read
What GSM means
GSM stands for grams per square metre. It is the weight of one square metre of fabric, and it is the most common way to describe how heavy a knit fabric is. Higher GSM generally means a thicker, more substantial fabric; lower GSM means lighter and more drapey.
In the United States fabric weight is often quoted in ounces per square yard (oz/yd²). As a conversion, 1 oz/yd² is roughly 33.9 GSM — so a “6 oz” tee fabric is around 200 GSM.
GSM is useful, but it is not the whole story. Two fabrics at the same GSM can feel very different because of fibre, yarn, knit structure and finishing.
General weight ranges — T-shirts
These ranges are general industry guidance, not a fixed specification. Exact weights and availability are confirmed per style when you get a quote.
- Lightweight, roughly 120–150 GSM: soft and breathable, good for summer, layering, and budget promo tees. Can look thin in light colours.
- Midweight, roughly 160–200 GSM: the everyday retail range. A balance of drape, durability and opacity.
- Heavyweight, roughly 220–300 GSM and above: structured, opaque, and popular for streetwear, boxy and oversized fits. Feels premium but is warmer and costs more in fabric and shipping.
General weight ranges — hoodies and sweatshirts
Again, general guidance only:
- Lightweight, roughly 240–280 GSM: spring and layering pieces, often French terry.
- Midweight, roughly 300–350 GSM: a common all-season hoodie weight.
- Heavyweight, roughly 380–500 GSM and above: thick, structured streetwear hoodies. Heavier fabric needs strong rib and careful construction so cuffs and hems keep their shape.
Common knit fabrics
- Single jersey: the classic T-shirt fabric. Smooth on the face, looped on the back, with natural stretch.
- Rib (1×1, 2×2): stretchy and elastic; used for collars, cuffs, hems and fitted tops.
- Interlock: a double-knit that is smooth on both sides, thicker and more stable than single jersey at a similar weight.
- Piqué: a textured knit used mainly for polo shirts.
- French terry (loopback): looped on the inside, smooth outside. Lighter and more breathable than fleece; popular for hoodies, sweatshirts and joggers.
- Fleece (brushed back): the loops on the inside are brushed into a soft, warm pile. The classic winter hoodie fabric.
Fibre: cotton, blends and more
- 100% cotton: soft and breathable; the default for many tees. Combed and ring-spun cotton yarns are smoother and softer than carded, open-end yarns, and usually cost more.
- Cotton-polyester blends: add durability, reduce shrinkage and wrinkling, and can be lighter on cost. Often written as CVC (chief value cotton, mostly cotton) or by percentage, e.g. 60/40.
- Spandex / elastane: a small percentage adds stretch and recovery, common in fitted tops and rib.
- Organic or recycled fibres: buyers often ask for these. Claims such as “organic” normally need certification from the fabric supply chain. Ask your factory which documents the fabric supplier can provide; we do not list certificates on this site.
Yarn count, briefly
For cotton jersey you may see numbers such as 20s, 30s, 32s or 40s. This is the yarn count (in the English cotton count system). A higher number means a finer yarn: 40s feels smoother and finer than 20s. Yarn count and GSM work together — a fine yarn knitted densely can still be fairly heavy.
Shrinkage and finishing
Cotton knits shrink, especially in length, unless they are treated. Ways to manage this:
- Pre-shrunk / compacted fabric at the mill.
- Garment washing after sewing, which also softens the hand-feel and can give a vintage look.
- Garment dyeing, where the finished garment is dyed; it gives a lived-in colour but adds shrinkage you need to plan for in the pattern.
Always wash-test the sample and re-measure. Our sampling guide explains how.
Matching fabric to your product
- Everyday brand tee: midweight jersey, combed cotton; regular or relaxed fit.
- Streetwear oversized tee: heavyweight jersey, boxy cut, dropped shoulder; consider a garment wash.
- Kids’ tee: soft midweight jersey; check your market’s rules for children’s clothing first (see our kids’ T-shirt page).
- All-season hoodie: midweight French terry or fleece.
- Winter / premium hoodie: heavyweight fleece with sturdy rib.
- Joggers: match the hoodie fabric for sets, or a slightly lighter weight for comfort.
- Polo: piqué or jersey, with a firm rib collar.
How to specify fabric to a factory
Write down what you know and let the factory fill in the rest:
- Fabric type (jersey, French terry, fleece, rib, piqué)
- Composition (e.g. 100% cotton, or a blend percentage)
- Target weight in GSM, or “like this reference garment”
- Colour, ideally with a Pantone or physical swatch
- Hand-feel and finish (soft, dry, washed, brushed)
- Any special needs: low shrinkage, high opacity, stretch
If you are not sure, send a reference garment whose fabric you like. A factory can usually match or suggest the closest available option and confirm it with the quote.
At Anlai, fabric and weight are confirmed per style with the quote — tell us what you are aiming for. See custom T-shirts, hoodies and sweatshirts, or request a quote.