GSM Explained: How It Works in Performance Sportswear
GSM is best understood as grams per square metre, the standard measure of fabric weight. This entry explains how it behaves inside a finished garment rather than only in the laboratory.
What the term means
grams per square metre, the standard measure of fabric weight, which is why the value appears on almost every technical data sheet. Working figures for GSM normally sit around 140-320 GSM for activewear in mainstream production. Note ISO 3801 fabric mass on the tech pack so nobody tests against an older revision.
Why it matters in practice
it predicts coverage, warmth and cost more reliably than thickness, so it influences buying decisions more than most buyers expect. Record elastane content alongside GSM, because blends shift the measured value. A result outside 140-320 GSM for activewear usually points to process drift rather than to the fibre itself.
Typical values seen in activewear
140-320 GSM for activewear. Ranges vary by construction, so compare like with like. Keeping reference values for GSM lets suppliers quote without extra sampling rounds. Ask for conditioning details together with ISO 3801 fabric mass, since both affect the reading.
How it is measured
ISO 3801 fabric mass is the reference normally quoted on a test report. Working figures for GSM normally sit around 140-320 GSM for activewear in mainstream production. Note ISO 3801 fabric mass on the tech pack so nobody tests against an older revision.
Frequent mistakes
Comparing results from different standards, testing unwashed fabric, and writing the target without tolerance are the common errors. Record elastane content alongside GSM, because blends shift the measured value. A result outside 140-320 GSM for activewear usually points to process drift rather than to the fibre itself.
