If you have ever ordered printing, you have been asked about GSM. It sounds technical, but the idea behind it is simple, and knowing it means you can ask for the right paper instead of guessing.
What GSM actually means
GSM stands for grams per square metre. It is the weight of one square metre of that paper. A 300 GSM card weighs 300 grams per square metre; standard office paper at 80 GSM weighs 80 grams per square metre.
Because paper is sold by weight, GSM is also how the trade names a stock. When a printer says "300 GSM art card", they mean a coated card of that weight — and everyone in the trade knows what to expect from it.
Why it matters more than "thick"
People often say "thick paper" when they mean heavy paper, but the two are not the same thing. GSM measures weight, not caliper (actual thickness in millimetres). A heavily coated 300 GSM sheet can measure thinner than an uncoated 300 GSM sheet of the same weight, because coating is denser than paper fibre.
In practice, GSM is the number that predicts how a printed piece will feel in the hand, so it is the number worth specifying.
Common GSM by job
| Job | Typical GSM | Why |
|---|---|---|
| Office paper, letterheads | 70–100 | Must feed reliably through laser printers and take a signature |
| Flyers, handbills | 130–170 | Holds its shape when handed out without being costly |
| Brochures, catalogues | 150–250 | Heavy enough to feel deliberate, light enough to fold and bind |
| Visiting cards | 300–350 | Substantial in the hand and cuts cleanly with a crisp edge |
| Rigid boxes, covers | 400+ | Structural, usually mounted to board for packaging |
When heavier is the wrong choice
It is tempting to assume the heaviest paper gives the best impression. It often does not:
- Folding. A very heavy uncoated sheet cracks along the fold unless it is scored first. For a folded card or a brochure, an extremely heavy stock can be more fragile at the fold, not less.
- Postage and courier. Paper weight is part of the parcel weight. On a large mailing, a heavier sheet adds real cost.
- Binding. Thick paper in a saddle-stitched booklet pushes the spine open and can make the pages spring back.
- Laser printing. Very heavy sheets may not feed through a desktop printer at all, which matters for letterheads and forms you print in-house.
How to choose without overthinking it
Start from what the piece has to survive. A card goes in a wallet, so it needs to stay flat and unfrayed — 300 to 350 GSM. A flyer is handed out and discarded, so a mid weight keeps costs sensible. A letterhead goes through a printer, so it has to be light enough to feed.
If you are unsure, ask to feel the stock. Paper is one of the few things where handling a sample tells you more than any specification — which is why the swatch books at our Anderkilla counter get used so often.
If you are choosing between surface finishes rather than paper weight, see Matte vs Glossy Visiting Cards. For the full specification, see Business Card Specifications.