Paper Weight: Converting GSM to Pounds for Bond and Cover Stock
October 29, 2026
Paper weight is expressed differently around the world. Outside the US, it is grams per square meter (gsm or g/m²), a direct measure of density. In the US, it is the weight in pounds of a ream (500 sheets) of the paper's basic size, and the basic size depends on the paper category, which makes pounds confusing: 20 lb bond is lighter than 80 lb cover, but 80 lb text is much thinner than 80 lb cover.
Conversion factors: for bond (basic size 17 × 22 inches), lb = gsm × 0.2661. For cover (20 × 26 inches), lb = gsm × 0.3697. For text or book (25 × 38 inches), lb = gsm × 0.6758.
Skip the math and get your answer instantly:
Open the Weight Converter →Common Conversions
Standard copy paper of 20 lb bond is about 75 gsm (75 × 0.2661 = 19.96). 24 lb bond is 90 gsm, 28 lb bond about 105 gsm, and 32 lb bond about 120 gsm. For heavier stock, 80 lb cover is 216 gsm (216 × 0.3697 = 79.9), and 100 lb cover is about 270 gsm. 100 lb text is 148 gsm. A postcard is typically 14 pt to 16 pt thick, about 300 to 350 gsm. Business cards: 300 to 350 gsm (110 lb cover is about 300 gsm). Thickness in points (pt) or mils is separate: 1 pt = 0.001 inch.
| Grams per m² (gsm) | Bond (lb) | Cover (lb) | Typical use |
|---|---|---|---|
| 75 | 20 | 28 | Everyday copy paper |
| 90 | 24 | 33 | Letterhead, double-sided printing |
| 120 | 32 | 44 | Premium documents, brochures |
| 216 | 58 | 80 | Light cardstock, covers |
| 300 | 80 | 111 | Business cards, postcards |
Choosing Paper
For double-sided printing, choose 24 lb or heavier to limit show-through. For flyers, 28 to 32 lb bond or 80 lb text feels substantial. For report covers, use 80 to 100 lb cover. Check your printer's maximum paper weight, since many desktop inkjets and laser printers handle up to 200 to 220 gsm. Heavier paper increases postage, so for mailers calculate the weight: 100 sheets of 20 lb letter paper weigh about 1 pound (500 sheets weigh about 5 pounds, equal to 2.27 kg).
Weight of a Sheet and a Ream
A sheet of A4 paper is 0.2101 × 0.2970 = 0.0624 m². At 80 gsm: 0.0624 × 80 = 4.99 g, so about 5 g, a handy figure. A ream of 500 sheets weighs 2.5 kg. US Letter is 0.0603 m², so a sheet of 75 gsm is about 4.5 g, or 0.16 ounce. Use these numbers to estimate the postage of a mailing: an envelope (about 6 g) plus 3 sheets (15 g) is 21 g.
Caliper and Opacity
Weight and thickness are related but not identical; coated papers may feel heavier or thinner than uncoated papers of the same gsm. Opacity depends on the fibers and the filler. Ask your printer for samples and specifications before a big run.
Frequently Asked Questions
How do I convert gsm to pounds of bond?
Multiply gsm by 0.2661.
What gsm is 20 lb bond?
About 75 gsm.
What is 80 lb cover in gsm?
About 216 gsm.
Why are US pound weights confusing?
The basic sheet size differs by paper category.
How much does an A4 sheet of 80 gsm weigh?
About 5 grams.