GSM is one variable.
Construction, yarn, knit or weave, finish and colour can change the way two fabrics at the same weight behave.
Free sourcing tool
Sportswear Fabric & GSM Selector
GSM helps organise a fabric discussion, but it does not prove warmth, opacity, durability, stretch or moisture management on its own.
Results are a family-level starting point, not a lab result or stock confirmation.
Approve a physical reference.
Record the proposed composition, weight, stretch, handfeel, colour and test requirements on the agreed swatch or sample.
Keep claims evidence-based.
Wicking, UV, abrasion, pilling and colourfastness claims need an agreed method and evidence for the selected material.