Understanding Paper
Weight: Text vs. Cover.

The pound is not the weight of one sheet

US paper weight is not the weight of a single sheet — it is the weight, in pounds, of a ream of 500 sheets at that paper grade’s traditional basic size, the size the sheet was cut down from before it became letterhead, or a cover, or whatever it ends up as. That basic size is different for different paper grades, and that single fact is the whole explanation for why “80 lb” means two different things.

Different grades, different basic sizes

• Bond / writing — basic size 17″ × 22″. Ordinary letterhead and copy paper.
• Text / offset — basic size 25″ × 38″. Flyers, brochure bodies, book pages.
• Cover — basic size 20″ × 26″. Business cards, postcards, covers and anything meant to feel stiffer.

A cover sheet’s basic size is much smaller than a text sheet’s. So 500 sheets of 80 lb cover, cut at the smaller 20 × 26 size, and 500 sheets of 80 lb text, cut at the larger 25 × 38 size, weigh the same — which means each individual cover sheet is carrying far more paper per square inch than each individual text sheet. That is why 80 lb cover feels like stiff card stock and 80 lb text feels like a heavy sheet of paper, not cardboard. The number alone tells you nothing until you know which grade it is measured against.

GSM sidesteps the whole system

Grams per square meter (gsm) measures mass per unit area directly, with no reference to any basic sheet size or paper grade. A 216 gsm sheet is a 216 gsm sheet whether it is labeled text, cover or index in the US system, which is why gsm is the standard used almost everywhere outside the US and the more reliable number for comparing two stocks across different American grade names.

Commonly published approximate conversions

These are widely used trade approximations, not exact physical conversions — actual caliper and weight vary somewhat by manufacturer and finish, so treat them as a starting point rather than a certified figure:

• 20 lb bond is roughly 75 gsm
• 24 lb bond is roughly 90 gsm
• 60 lb text is roughly 90 gsm
• 80 lb text is roughly 120 gsm
• 100 lb text is roughly 150 gsm
• 65 lb cover is roughly 175 gsm
• 80 lb cover is roughly 215 gsm
• 100 lb cover is roughly 270 gsm

The paper weight converter runs these conversions both directions without the arithmetic.

Weight is not the only thing that decides how a sheet behaves

Caliper (actual thickness), opacity (whether printing on one side shows through the other) and finish (coated gloss, coated matte, or uncoated) all vary somewhat independently of weight. Two 80 lb text sheets from different mills can feel noticeably different in thickness and stiffness. Cover-weight decisions show up most on business cards, postcards and covers, and offset’s wider stock range (see offset printing) opens up heavier and more textured options than a digital press can feed. When it genuinely matters, confirm a stock against a real sample — which is exactly what a hard-copy proof is for; see what to check on a print proof.