The weight of paper per square meter, measured in g/m². Higher GSM generally means thicker, stiffer, stronger sheets—and higher material/shipping cost.
How to read it: 120 gsm = a 1 m² sheet weighs 120 grams.
Typical ranges:
50–80 gsm: inserts, inner wraps
90–150 gsm: shopping bags, labels, light covers
200–350 gsm: paperboard, folding cartons
≥400 gsm: heavy board, stiffeners
GSM vs thickness: not a fixed conversion—different papers with the same GSM can have different calipers (µm) due to density/bulk.
Selection tip: choose GSM by load/stiffness needs, then confirm with your supplier the caliper, Cobb (water absorbency), and printability match your process.