Paper weight conversions: lb, pt, and gsm
US paper weights in pounds are basis weights: the weight of 500 sheets of that grade's basis size, and each grade has a different basis size. That is why 80 lb text (about 118 gsm) is a much lighter paper than 80 lb cover (about 216 gsm). Grams per square meter (gsm) measures the paper itself with no grade convention, so it is the only scale where a bigger number always means a heavier sheet. Points (pt) measure caliper thickness, not weight, in thousandths of an inch.
Why the pound scale confuses everyone
A ream of 500 sheets of the grade's basis size defines the basis weight. Text and book papers use a 25 x 38 inch basis sheet, cover uses 20 x 26, bond uses 17 x 22, and bristol and index have their own. Because the basis sheets differ in area, equal pound numbers across grades do not mean equal papers.
The practical consequence: never compare pound weights across grades. Convert to gsm first, or compare within one grade only.
Common equivalents
Approximate equivalents worth memorizing, rounded as the trade rounds them:
- 20 lb bond is about 75 gsm, ordinary office paper
- 50 lb text is about 74 gsm; 60 lb text about 89 gsm; 70 lb text about 104 gsm; 80 lb text about 118 gsm; 100 lb text about 148 gsm
- 65 lb cover is about 176 gsm; 80 lb cover about 216 gsm; 100 lb cover about 270 gsm; 130 lb cover about 352 gsm
- 10 pt board is roughly 0.010 inch thick; 14 pt roughly 0.014 inch; caliper varies with the sheet's construction, so pt does not convert exactly to gsm
Points measure thickness, not weight
Board grades like 12 pt or 14 pt C2S are specified by caliper: one point is one thousandth of an inch. Two boards of the same caliper can differ in weight depending on density and coating, which is why pt-to-gsm tables are approximations. When stiffness is the requirement, specify caliper; when mailing weight matters, check gsm.
Put the numbers to work in the PressBench estimator, or check the reference tables.
Frequently asked questions
Why is 80 lb cover heavier than 80 lb text?
Because the pound figure is the weight of 500 sheets of each grade's own basis size, and the cover basis sheet (20 x 26 in) is much smaller than the text basis sheet (25 x 38 in). The same 80 pounds spread over less area means a heavier paper: about 216 gsm against about 118 gsm.
What does gsm mean in paper?
Grams per square meter: the weight of one square meter of the paper. It carries no grade convention, so gsm values compare directly across every paper type, which US basis weights do not.
How thick is 14 pt card stock?
0.014 inches, since one point is one thousandth of an inch. Points measure caliper thickness rather than weight; a 14 pt board is commonly in the neighborhood of 300 to 350 gsm depending on its construction.
What weight of paper is normal office printer paper?
Standard copy paper is 20 lb bond, roughly 75 gsm. A typical flyer stock is 80 or 100 lb text (about 118 to 148 gsm), and a typical business card is 14 pt board or around 100 to 130 lb cover.