GSM How to Read It on a Lab Report
Laboratory reports present GSM in a compact format. Knowing what each line means prevents misreading.
Definition reminder
grams per square metre, the standard measure of fabric weight. 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.
Common report layout
The report states method ISO 3801 fabric mass, sample description, conditioning, and the measured result. 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 result
Values near 140-320 GSM for activewear usually indicate a conforming lot, assuming the fabric matches the sample submitted. 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.
Red flags
Missing revision numbers, unusual conditioning, and results without units all signal unreliable data. 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.
Questions to ask
Ask the laboratory for the standard revision and sample description before accepting or rejecting a result. 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.
