GSM to Pound (lb) Paper Weight Calculator
Convert paper weight in GSM to the US basis weight in pounds for any grade — because a 20 lb bond and an 80 lb text can weigh almost the same.
How it works
lb = GSM × basic-sheet-area(sq in) ÷ 1406.14 (500-sheet ream at the grade’s standard size)
GSM (grams per square meter) is an absolute measure — it means the same thing for any paper. US basis weight in pounds is the weight of a 500-sheet ream cut to that grade’s standard “basic size,” which differs by grade: bond is 17×22 in, text 25×38, cover 20×26. That is why a 20 lb bond and a 50 lb text are nearly the same thickness despite the very different pound numbers, and why you must pick the grade to convert correctly.
Worked example
For text/book stock (basic size 25×38 = 950 sq in), 120 g/m² converts to 120 × 950 ÷ 1406.14 ≈ 81 lb text. The same 120 g/m² on cover stock (20×26) would read as only about 44 lb cover.
Sources: Paper density and basis weight
Frequently asked questions
Why do I need to choose a paper grade?
Because US pound ratings are tied to each grade’s standard sheet size. The same GSM converts to different pound numbers for bond, text, cover, index and tag, so the grade is essential.
Is GSM more reliable than pounds?
Yes for comparing across grades — GSM is an absolute weight per area. Pound ratings only make sense within a single grade.
What is a typical cardstock weight?
Common cardstock runs about 200-350 g/m², which is roughly 74-130 lb cover. Standard copy paper is around 75-90 g/m² (20-24 lb bond).
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This calculator is for educational purposes. Double-check important results before acting on them.