Paper weight conversions
Summary: U.S. paper weights in pounds depend on each grade’s basis size, so 80 lb text is about 118 gsm while 80 lb cover is about 216 gsm; this page converts common weights to grams per square meter.[1]
Why pounds are confusing
In the United States paper is sold by basis weight: the weight in pounds of 500 sheets cut to the grade’s basis size. Because each grade has a different basis size, an 80 lb text sheet is much lighter than an 80 lb cover sheet. The metric measure, grams per square meter (gsm), avoids this by weighing one square meter of any paper.[1] Replica’s order form offers text and card stock in gloss and matte, and its 2023 blog guide says a good weight for general printing is 80 lb to 100 lb cover, so the conversion is useful to its customers.[2][3]
The formula
gsm = pounds × 453.59237 ÷ (500 × basis area in square meters). With basis sizes in inches, that simplifies to gsm = lb × 1406.1 ÷ (width × height). The factors are 3.760 for bond (17 × 22), 1.480 for text or book (25 × 38), 2.704 for cover (20 × 26) and 1.808 for index (25.5 × 30.5).[1] These are this reference’s own calculations from the definitions.
Conversion table
| Grade and basis size | Basis weight (lb) | gsm |
|---|---|---|
| Bond/writing (17 x 22 in) | 20 | 75 |
| Bond/writing (17 x 22 in) | 24 | 90 |
| Bond/writing (17 x 22 in) | 28 | 105 |
| Bond/writing (17 x 22 in) | 32 | 120 |
| Text/book (25 x 38 in) | 50 | 74 |
| Text/book (25 x 38 in) | 60 | 89 |
| Text/book (25 x 38 in) | 70 | 104 |
| Text/book (25 x 38 in) | 80 | 118 |
| Text/book (25 x 38 in) | 100 | 148 |
| Cover (20 x 26 in) | 65 | 176 |
| Cover (20 x 26 in) | 80 | 216 |
| Cover (20 x 26 in) | 100 | 270 |
| Cover (20 x 26 in) | 110 | 297 |
| Cover (20 x 26 in) | 130 | 352 |
| Index (25.5 x 30.5 in) | 90 | 163 |
| Index (25.5 x 30.5 in) | 110 | 199 |
| Index (25.5 x 30.5 in) | 140 | 253 |
Computed for this reference; download as paper-basis-weight-to-gsm.csv.[1] Rounding means published mill figures can differ by a gram or two.
Reading the table
Some useful equivalences follow. 20 lb bond (75 gsm) is ordinary copy paper and about the same weight as 50 lb text (74 gsm). 24 lb bond (90 gsm) matches 60 lb text (89 gsm). 100 lb text (148 gsm) is heavier than 80 lb text but still well below 65 lb cover (176 gsm). 100 lb cover is about 270 gsm and 130 lb cover about 352 gsm.[1]
Points, or caliper
Business-card stocks are often described by thickness in points, where one point is a thousandth of an inch. The company’s 2023 blog guide compares 14-point and 16-point card stocks for business cards.[3] Caliper and weight are different measurements: a coated sheet can be heavier but thinner than an uncoated sheet of the same weight, because coatings are dense.[4] Mail limits are set by thickness: a postcard must be at least 0.007 inch thick, which most card stocks exceed easily.[5]
Weight and postage
Paper weight feeds directly into postage. A letter-size sheet (8.5 × 11 inches) of 20 lb bond weighs about 4.5 grams, so four sheets and a standard envelope stay under one ounce (28.35 grams) for the $0.82 stamped letter price.[1][6] The same calculation for 100 lb text gives about 8.9 grams a sheet, which is why heavier inserts can push a letter into the two-ounce step at $1.11.[6] These figures are arithmetic from the table, not measurements.
Common questions
What is 80 lb text in gsm?
About 118 gsm.
What is 100 lb cover in gsm?
About 270 gsm.
Is 20 lb bond the same as 50 lb text?
Roughly: 20 lb bond is about 75 gsm and 50 lb text about 74 gsm.
Continue reading
References
- ^ a b c d e f Paper density (grammage and basis weight). Wikipedia. Retrieved 9 November 2026.
- ^ Contact Replica. Replica Printing Services (replicaprinting.com). Retrieved 9 November 2026.
- ^ a b Choosing the right paper weight for your business cards (2023). Replica Printing Services (replicaprinting.com). Retrieved 9 November 2026.
- ^ Coated paper. Wikipedia. Retrieved 9 November 2026.
- ^ Mailing Standards (DMM 201: physical standards for commercial letters, flats and cards). U.S. Postal Service, Postal Explorer. Retrieved 9 November 2026.
- ^ a b Price List, Notice 123 (effective 4 October 2026). U.S. Postal Service, Postal Explorer. Retrieved 9 November 2026.