Paper weight in gsm: cover, text and what a stapler can handle

Paper weight is sold in grams per square metre, written gsm. It is the weight of one sheet cut to a square metre, so it measures how substantial the paper is, not how big the sheet is. A sheet of A4 is about one sixteenth of a square metre, so an 80 gsm A4 sheet weighs a little under five grams.

The common weights

Rough bands, as most suppliers describe them:

• 60 to 80 gsm. Newsprint-like to standard office paper. Fine for text pages, and thin enough that print shows through if the ink is heavy.
• 90 to 120 gsm. A firmer text paper. Good for photographs on uncoated stock, and a sensible step up for a booklet that will be handled.
• 130 to 170 gsm. Light card. Works as a text paper for a very short booklet, or as a cover for a thin one.
• 200 to 300 gsm. Card. Used for covers and postcards. It does not fold cleanly without scoring.

Treat these bands as approximate. Different mills call the same thing by different names, and coated and uncoated papers of the same gsm feel different. A coated 130 gsm sheet feels stiffer and thinner than an uncoated 130 gsm sheet because coating is dense and the sheet is more compact.

Weight is not thickness

Gsm describes mass, and thickness depends on how loosely the fibres are packed. A bulky, uncoated paper is thicker than a calendered, coated paper at the same gsm. If thickness matters for creep or for the spine, ask for the caliper, usually given in microns, or measure a stack with a ruler and divide. The creep estimate on this site uses a typical thickness for each weight and says so.

Choosing for a stapled booklet

For a saddle-stitched booklet, a common recipe is 80 to 100 gsm for the inside and 150 to 200 gsm for the cover. The cover is the outermost sheet and does a lot of work: it protects the pages, it carries the title and it bears the staples. A heavier cover makes the booklet feel finished, but also adds to thickness and to creep, and heavier cards need to be scored before folding so the crease does not crack.

If you print everything on the same paper at home, use 90 to 100 gsm if your printer allows it. Ordinary 80 gsm is perfectly workable for sixteen pages or fewer.

What a stapler can handle

A desk stapler is rated in sheets of 80 gsm, with typical models handling around twenty to twenty-five sheets of paper. A long-reach saddle stapler is built for the job and can place staples through the centre fold. For folded booklets the count of layers is twice the number of sheets, since each folded sheet has two layers at the spine. Heavier paper counts for more, so as a rule of thumb, keep the total below about half of the stapler’s rated capacity to get a clean clinch.

What a home printer can handle

Most inkjet and laser printers take up to 120 or 160 gsm from the manual feed, with the manual listing a maximum. Double-sided printing is more demanding than single-sided. Heavier stock can jam, smear on a laser fuser, or fail to turn properly in the duplexer. If your sheet is imposed so the back must line up with the front, test a single sheet before printing a run.

Opacity and show-through

Thin paper lets the other side show through, which matters most for photographs and solid blocks of colour. Ask for an opacity figure if the shop gives one. As a practical test, print a heavy block of black on one side and look at the other against a window. If the ghost is distracting, step up in weight or place images on facing pages so their shadows overlap with each other and the eye reads them as part of the design.

Environmental notes

Recycled paper is available in nearly all the weights above, and the choice of finish changes the feel more than the recycled content does. If a certification matters to you, ask for the mill’s own documentation rather than relying on a label alone.

A short decision

Text at 90 gsm, cover at 170 gsm, and a quick test of the staples: that combination covers most small zines. Move up or down once you have held a printed sample and decided it feels right.