Summary
GSM stands for grams per square meter, and it is the one line on a teamwear specification that decides how a jersey feels, drapes and wears. Most guides stop at telling you which weight to pick. This one covers the part that decides whether you actually get it: what the figure measures, how to convert it when your spec is written in ounces, how to put it into a brief that a factory has to answer, and how to check the cloth that arrives.
What GSM measures, and what it does not tell you
GSM is the weight of one square meter of finished fabric, in grams. It is not thickness, not yarn count, and not a quality score.
Two knits can both read 160 gsm and feel completely different, because structure, yarn and finishing all change the hand. Within one knit family, weight is a reliable guide to hand, drape and shape retention. Across families it is noise, which is why a weight copied from one sport to another often disappoints.
It does not measure breathability either. Airflow comes from the structure of the knit, not the number: our ice hockey range runs on a single 250 gsm low-elastic hole mesh, described on the product page as a breathable open-hole knit with a firm hand. A spec that names only the weight has said very little.
Converting grams to ounces without rounding twice
If you buy to a US mill spec, your weight will arrive in ounces per square yard while a factory quotes grams per square meter. The conversion is fixed: one ounce per square yard equals 33.906 grams per square meter, so divide the gsm figure by 33.906 to reach ounces.
On that basis our own grades sit at roughly 3.2 oz for 110 gsm, 4.7 oz for 160 gsm, 5.3 oz for 180 gsm, 7.4 oz for 250 gsm and 8.8 oz for 300 gsm. State the unit you were given and let the factory convert once, rather than rounding in both directions.
This is the weight of the cloth, not the chargeable weight a freight invoice bills on: two numbers that share a word and nothing else.
The weights our styles run on, sport by sport
These are grades a factory actually runs, and the spread is wider than most buyers expect. Read them as the menu you are choosing from, not as a recommendation.
Basketball runs three. The reversible ZK-B02 uses a lightweight bird-net mesh with an even breathable eyelet surface at 110 gsm. The ZK-B01 single-side build offers a 175 gsm performance hole mesh as standard, with a 250 gsm low-elastic hole mesh as the heavier option.
Soccer runs bird eye at 150 to 180 gsm in two weights, shiny pin eye at 160 gsm and football net at 160 gsm. All three are 100% polyester and hold embroidery and twill appliqué well.
Baseball uses a different knit family: bird net at 180 and 220 gsm, plus a polyester-spandex double knit at 260 gsm, the heaviest of the three and the closest to a woven-look jersey.
Ice hockey is deliberately narrow, one 250 gsm low-elastic hole mesh across the whole range, with a firm hand that holds its shape through repeated washing. Marathon and running sit at the other end on a single 160 gsm butterfly mesh with a light hand.
Shorts run bright-luster plain at 150 gsm, hole mesh at 180 gsm and polyester-spandex double knit at 210 gsm. Tracksuits run a double knit at 270 gsm and a jacquard knit at 300 gsm.
Same weight, different hand: why the knit family matters
A weight on its own does not identify a fabric. Bird eye, bird net, hole mesh, butterfly mesh, double knit and jacquard knit are different structures, and each behaves differently at the same number.
Our own product pages make the point in a way worth copying into your own brief. The baseball page states that its bird net and double knit are a different knit family from the bird eye listed on the soccer page, and asks buyers to quote against the weights listed on the baseball page rather than carrying a soccer figure across. That is a factory telling you that a weight without a knit family is an incomplete specification.
So write two words, not one: the knit family and the weight. Bird eye 180 gsm and bird net 180 gsm are not interchangeable, even though the arithmetic is identical.
Weight and decoration: why embroidery wants a firmer base
Weight and decoration are linked, though not in the way buyers assume. Sublimation bonds ink into the fibers, so it places no structural load on the cloth and works across the whole range. Embroidery is stitched and adds bulk, so it benefits from a firmer base.
Our basketball page says this directly: the 175 gsm mesh is described as a firm base for embroidery, and the 250 gsm grade as offering better shape retention under embroidery. The same logic runs through the hockey range, where crests are embroidered or applied as twill on top of a 250 gsm sublimated body.
Note what the pages do not say: they describe a firmer hand and better shape retention, not a threshold below which embroidery is impossible. If your crest will be stitched and your grade is the lightest in the range, ask directly.
Writing the weight into your brief and your purchase order
This is where weight specifications quietly fall apart. A number agreed in an email thread is not a specification; a number on a quotation accepted by both sides is.
The line you want on the PO names the garment part, the knit family and the weight. Body first, then the rest, because a jersey is not one weight: side panels, collar rib and trims can all be different fabrics, and a single number for the whole garment invites an unintended substitution.
Our own paperwork is built around that limit rather than around a promise. For the reversible basketball build, the product page states that fabric weight and the exact layer construction are confirmed on your written quotation. The tracksuit page is blunter, noting that weights are as labeled on the fabric swatches and that the weight for your order is confirmed on your written quotation. The quotation is the document that binds the weight, so make sure it is on there before you pay.
Two thresholds shape the rest of the brief. The minimum order is 10 pieces per design, with a set counting as one piece, and bulk production runs 10 to 15 working days after the deposit is received and the design or sample is approved. The cost logic behind a quotation is covered in our guide to MOQ and pricing for custom jerseys; if sizes are the open question, the team uniform sizing guide explains how to read a factory size chart.
How to check the weight you were sent
Two checks matter, and the cheaper one happens before you commit.
A digital proof comes first and is free: once your design files, specs and size breakdown are confirmed, we prepare a full mockup front and back showing logo, colors, numbers, names and placement, usually within three to five days, with up to five rounds of revisions. A proof cannot show hand, drape or opacity, so it settles artwork and nothing else.
A physical sample costs US$15 to 50 per style depending on design and customization, takes about seven days to make, the fee is not deducted from your bulk order, and sample shipping is paid by the buyer. It is the only way to judge the cloth before production, and once approved it becomes the reference.
For goods already delivered, the arithmetic is simple enough to run in a stockroom. Cut a square of known area from an offcut, twenty by twenty centimeters, or 0.04 square meters. Weigh it on a scale that reads to 0.01 g, then divide the weight in grams by 0.04. At 160 gsm that square should weigh about 6.4 g. A result far from the quotation line means a conversation, not a rounding error.
The short version
GSM describes a roll of cloth, not a finished jersey, and it is a specification rather than a ranking. Name the knit family and the weight together, write both onto the quotation, and check the delivered cloth with a twenty-centimeter square and a 0.01 g scale. That is the whole discipline, and it costs one garment to learn.
If you are choosing between two grades for an upcoming season, our sublimated jersey options page lists the performance fabrics we run, and the fastest way to get a weight confirmed against your own brief is to send your requirements with sport, quantity and delivery date.