T-shirt GSM explained: how to choose a fabric weight
GSM means grams per square metre. It's the standard way to state how heavy a knitted fabric is, and it's the first number a factory asks for when costing a T-shirt. Heavier fabric costs more, feels more substantial and holds its shape differently.
How GSM is measured
A cutter takes a circle of exactly 100 cm² from the finished fabric. The circle is weighed, and the weight in grams multiplied by 100 gives the GSM. Fabric is usually specified with a tolerance, typically ±5%.
Which weight for which T-shirt
| Weight | Feel | Typical use |
|---|---|---|
| 120–150 GSM | Light, soft drape | Summer tees, layering, women's fitted styles |
| 160–190 GSM | Mid-weight, all-round | Everyday retail tees, merch, uniforms |
| 200–240 GSM | Heavy, more structure | Premium basics, relaxed and boxy fits |
| Over 240 GSM | Very heavy, stiff at first | Heavyweight streetwear tees |
Our standard T-shirt range runs from 140 to 200 GSM. If you want something heavier, ask: we'll tell you what's possible for your style.
What GSM doesn't tell you
Two fabrics at 180 GSM can feel quite different. Specify these too:
- Yarn count. Finer yarn (a higher Ne number, such as 30s or 40s) makes a smoother, denser fabric than coarser yarn (20s or 24s) at the same weight.
- Combed or carded cotton. Combed cotton has shorter fibres removed, so it's softer and pills less.
- Knit structure. Single jersey, slub jersey and interlock behave differently at the same weight.
- Finishing. Compacting reduces shrinkage; enzyme and silicone washes soften the hand feel.
Shrinkage
Cotton knits shrink when washed unless the fabric is compacted. Agree a maximum shrinkage with the factory, often 5% or less in length and width, and ask for a wash test on the sample fabric.
How to write it in your brief
100% combed cotton single jersey, Ne 30s, 180 GSM ±5%, compacted, shrinkage under 5%.
Not sure? Send us a T-shirt you like and we'll match the fabric. See our T-shirts or request a quote.