GSM means grams per square meter of fabric
GSM stands for grams per square meter. A 220 GSM fabric weighs 220 grams for each square meter of material. A finished T-shirt uses a different amount of fabric depending on its size and cut, so it does not necessarily weigh 220 grams.
This distinction matters in an FSBuy spreadsheet. A shipping-weight field and a fabric-weight specification answer different questions. Keep them in separate notes. If a listing says only “250 g,” ask whether that is the finished item, a packed item or a fabric measurement before comparing it with another listing.
Some specifications use ounces per square yard. Multiply that figure by approximately 33.91 to express it in GSM. An ounce figure without an area unit is not enough to make this conversion.
180, 220 and 280 GSM: useful examples, not universal grades
There is no single fabric weight that every buyer should choose. A light-feeling layer and a substantial standalone tee serve different purposes. Start with how you plan to wear the item, then compare the fabric, cut and finish together.
Real product ranges show why weight and shape need separate attention. AS Colour’s published tee comparison describes its Staple as a regular-fit 180 GSM style, its Classic as a relaxed 220 GSM style, and its Heavy as a boxy, oversized 280 GSM style. Those are specific products with different cuts; their numbers are not a grading system for every T-shirt.
| Your starting point | What to compare alongside GSM | What not to assume |
|---|---|---|
| A tee to layer under another top | Body length, sleeve bulk and the feel you want | A heavier fabric will automatically layer better |
| A standalone everyday tee | Cut, surface finish and how the fabric hangs | The same GSM creates the same silhouette |
| A substantial, boxy look | Fabric specification plus the actual garment cut | A high weight alone creates an oversized fit |
Why two cotton tees at the same GSM can feel different
Fiber preparation and fabric construction still matter. Combed cotton and carded cotton describe different yarn preparation. AS Colour distinguishes its combed jersey from its less-soft carded cotton, while offering combed fabrics at several weights. This is a useful reminder that a weight number cannot describe the surface of a fabric.
Composition is another separate field. Read the percentage breakdown for the selected color, rather than treating “cotton feel” as a composition statement. A supplier’s description of its own fabric does not establish the composition of a different seller’s product.
For your comparison, use three columns: the claimed GSM, the stated fiber composition, and any finish or fabric description. Enter “not supplied” where information is missing. That preserves a meaningful difference between a documented specification and an attractive description.
Is a heavyweight T-shirt always better?
No. Weight describes one measurable property. It cannot by itself establish seam quality, colorfastness, shrinkage after washing or how comfortable a garment will feel to you. Those questions need their own evidence; a high GSM is not a substitute for it.
Avoid paying more purely because a title includes “heavyweight” or “premium.” If the seller provides neither a fabric weight nor a composition, there is little to compare numerically. You can keep the item as a style option while recording that its material specification remains unknown.
A practical way to compare two listings
Suppose one listing states 220 GSM cotton and another states 280 GSM cotton. These are hypothetical options, not tested products. First decide whether both could serve the same wardrobe role. Then record their composition, cut and care information. If the heavier option is also much wider, you are comparing two design choices, not isolating fabric weight.
Start with the feel and shape you want, then compare GSM, fiber content, cut and care information. If two tees differ in several of those areas, the GSM number cannot explain every difference between them. Use the T-shirt category to compare a few options, then check their measurements.