What is GSM paper weight?

Weight per area, not thickness

The measure is defined by area. Take a single sheet exactly one metre square and weigh it; if it weighs 150 grams, the paper is 150 gsm, whatever size the finished piece is cut to. That makes gsm a fair way to compare stocks across sheet sizes. It is closely related to thickness but not the same thing. A dense coated paper can be thinner than an uncoated paper of the same gsm, and bulky uncoated stocks can feel heavier in the hand than their number suggests. Printers in Australia, the UK and most of the world quote gsm. North American printers often quote pounds or point thickness instead, which Vistaprint's paper guide explains as weight in pounds or points, one point being a thousandth of an inch.

Matching weight to the job

Australian print shops give fairly consistent guidance. Paperlust describes 150 to 170 gsm as the most commonly ordered range in Australian commercial print, 150 gsm gloss as the most ordered weight for DL, A5 and A4 flyers, 115 gsm as the option for high volume budget leaflet drops, and 170 gsm gloss as the practical minimum for an A1 or A0 indoor poster that will not sag or curl. Letterbox Distributors describes 130 to 150 gsm as standard flyer territory and 170 to 200 gsm as premium flyer and pamphlet weight. The pattern is simple: pieces people hold briefly can be light, pieces that must stand up, last or signal quality should be heavier.

When weight changes more than feel

Weight affects postage, since mail is priced by weight bands and a heavier stock can push a mailout into a dearer band. It affects folding: heavy papers crack along a fold unless they are scored first, so brochures often use a lighter inside stock with a heavier cover. It affects show through, where a thin sheet printed on both sides lets dark areas ghost through to the other side. It affects distribution, because letterbox walkers carry a set weight per bundle and very light leaflets are harder to push through slots. It also affects durability: a menu, price list or rack card handled dozens of times a day wears out quickly on light paper, while the same design on a heavier stock stays flat and clean for weeks. And it affects cost, though on short digital runs the difference between 150 and 170 gsm is often small compared with setup and delivery.

Common mistakes

The most common is choosing the heaviest stock on offer for everything, which raises postage and makes folded pieces crack. The second is using light paper for a double sided flyer with large dark areas, so both sides show through. The third is assuming gsm alone decides quality; the coating, finish and brightness of the paper change how colours and photos look as much as weight does. The fourth is comparing gsm with pounds without converting, since the two systems measure differently. The fifth is not asking for a sample. Most shops will send or show paper samples, and holding the actual stock settles the choice in seconds.

Paper weight and the flyer builder

Paper weight is a print shop decision, not a design setting. The flyer builder has no paper, stock or finish option, and nothing in the exported file records one. A4 designs export as RGB PDF, PNG or JPG at 2480 by 3508 pixels, which is enough resolution for any common flyer stock. Choose the weight when ordering, based on how the flyer will be used: a letterbox drop, a counter handout, a menu that will be handled daily or a poster pinned to a wall. The open house example linked on this page is the kind of listing sheet handed to buyers at the door, where a sturdier stock around 150 to 170 gsm suits a piece people fold into a pocket and keep.

Questions people ask