Art and Craft Supplies
Paper weight, gsm to lb.
Roughly the same weight is sold as 20 lb bond, 50 lb text and 75 gsm. Pick the paper type, enter either number, and see every other way that weight is written.
lb = gsm x sheet area x 500 / 453.59. A 20 lb bond sheet is 75.2 gsm. A 140 lb watercolour sheet (22 x 30 in basis) is 298.3 gsm.
Paper weight
Conversion
Fill the form and press Calculate.
Worked example
A sheet of 90 gsm text paper (25 x 38 in basis). Area of the basis sheet is 25 x 38 = 950 sq in = 0.6129 m2, so 500 sheets at 90 g/m2 weigh 27,581 g, which is 60.8 lb. Weighed as bond (17 x 22 in) the same 90 gsm paper is 23.9 lb, and as cover (20 x 26 in) it is 33.3 lb. In the other direction, 20 lb bond is 75.2 gsm and 140 lb watercolour is 298.3 gsm; going back, 300 gsm watercolour paper works out to 140.8 lb.
How it works
US paper is sold by the weight in pounds of a 500-sheet ream cut to the "basis size" for its type, and the basis size differs by type, so 20 lb bond and 20 lb cover are very different sheets. Metric gsm is simply grams per square metre of one sheet, with no basis size. The converter finds the area of the basis sheet in square metres, multiplies by gsm and by 500 sheets to get grams per ream, and divides by 453.59237 g per pound.
The basis sizes used are the ream-size table on the Grammage page (bond 17 x 22, text 25 x 38, cover 20 x 26, index bristol 25.5 x 30.5, bristol and tag 22.5 x 28.5, watercolour 22 x 30, newsprint 24 x 36, all 500 sheets per ream; the Grammage table lists cover as 500 or 1000, and the 500-sheet basis is used here). Check the product page if a maker uses a different basis for its own range.
Sources and basis (opened 2026-10-08): ream (basis) sizes by paper type from Grammage (Wikipedia); 1 lb = 0.45359237 kg from Pound (mass) (Wikipedia); 1 in = 25.4 mm from Inch (Wikipedia).
FAQ
How do I convert gsm to lb for paper?
Pick the paper type, because pounds depend on the basis size. For bond, lb = gsm x 0.266. 80 gsm bond is 21.3 lb. The converter does every type at once.
How many gsm is 140 lb watercolour paper?
298.3 gsm using the 22 x 30 in basis. Conversely, 300 gsm is 140.8 lb.
Is 20 lb bond the same as 20 lb cover?
No. Cover is weighed on a 20 x 26 in sheet and bond on 17 x 22 in, so 20 lb cover is much lighter paper than 20 lb bond. Only gsm compares directly across types.
How heavy is 250 gsm card in lb?
As cover stock, 250 gsm is 92.5 lb.
Why do shops list a slightly different number?
Labels may be rounded and a maker can state its own basis size. Treat the converter as the exact arithmetic and the label as the product spec.
Disclaimer
Results are arithmetic from the numbers you enter. Paper makers may label products with rounded weights or their own basis sizes. Check the product data sheet before ordering.