Custom T-Shirts: GSM, Fabric Composition and Fit Explained

T-shirt GSM, fibre composition and fit describe different things. GSM expresses fabric mass in grams per square metre; composition identifies the declared fibres; fit concerns the garment's measurements and shape. None of these alone establishes the overall quality or suitability of a T-shirt for your collection.
In this guide
Keep the three decisions separate
Ask whether the stated weight refers to the finished fabric proposal and which measurement basis is used. Agree any acceptance tolerance rather than borrowing a number from an unrelated product.
| Term | What it describes | What it does not settle |
|---|---|---|
| GSM | Fabric mass per unit area | The entire feel, appearance or performance of the garment |
| Composition | Declared fibre content | The knit construction, finishing or fit |
| Fit | Measurements, silhouette and wearing allowance | The material specification by itself |
Compare fabrics in an assembled T-shirt
Review identified swatches alongside the sewn sample. Record neckline, sleeve, body and hem measurements, and state the intended fit reference. If comparing two materials, keep the pattern and construction constant where practical so that material and silhouette changes are not confused.
Resolve care and finishing questions before approval
- Identify the fabric construction and any requested finish.
- Ask which cleaning and measurement conditions support the review.
- Check neckline and seam appearance on the assembled proposal.
- Approve branding on the intended fabric, not only on a screen.
- Keep the approved material and fit revisions with the size breakdown.
Mistakes to avoid
- Using a higher GSM as a universal quality ranking.
- Comparing body measurements with flat garment dimensions.
- Approving the unwashed appearance while leaving care-review questions unresolved.
Prepare the next decision
Send the material fields and measurement sheet together. Ask the supplier to identify the proposed fabric and sample configuration before confirming the manufacturing quotation.
For catalogue context, explore the T-Shirts collection and review Stepped-Hem V-Neck T-Shirt as a catalogue design reference; confirm its documented concept/sample status before using it in a production brief. Discuss your development requirements through the manufacturing and sampling process.
Sources and further reading
Let’s Discuss Your Next Collection
Share your references, specifications and requested quantities. Materials, feasibility, pricing and timing are confirmed for your project.

