Paper is described by weight and type.
The number in a paper weight (such as the “20” in “basis 20” or “substance 20” or “20-lb bond”) is the weight of 500 sheets of that paper in a standard sheet size whose dimensions are defined for that particular type of paper, regardless of the actual size of the sheets being sold.
For example, a package of 8½ by 11 inch typing paper might be marked “20-lb.” Typing paper is a variety of bond paper, and bond paper weights are based on a 17-inch by 22-inch sheet size, so 500 17-inch by 22-inch sheets of this paper would weigh 20 pounds. The standardized sizes are as follows:
| Grade | Dimensions on which basis weight is based |
To convert pounds to g/m2 multiply by |
To convert g/m2 to pounds multiply by |
|
|---|---|---|---|---|
| Bond | 17 inches by 22 inches. | Stationery, typing paper. Some speculate that this is the size of the largest sheet that could easily be made by one person when all paper was handmade. It is half of the nineteenth century “demy” size. |
3.760 | 0.266 |
| Coated | 25 inches by 38 inches. | 1.480 | 0.675 | |
| Text | 25 inches by 38 inches. | 1.480 | 0.675 | |
| Book | 25 inches by 38 inches. | 1.480 | 0.675 | |
| Offset | 25 inches by 38 inches. | 1.480 | 0.675 | |
| Cover | 20 inches by 26 inches. | The weight of cover stock is often given in points rather than pounds. Points measure the paper's thickness; 1 point = 0.001 inches. | 2.704 | 0.370 |
| Bristol | 22½ inches by 28½ inches. | Sometimes called printing bristol. | ||
| Index | 25½ inches by 30½. | Sometimes called index bristol. | ||
| Tag, newsprint | 24 inches by 36 inches. | Tag is the stock from which manila folders and shipping tags are made. | 1.627 | 0.614 |
Like wood, machine-made paper has grain. Folding with the grain produces a smooth fold; folding against the grain causes buckling and cracks. In paper catalogs the direction of the paper's grain is often indicated by underlining the dimension in which the paper grain runs. For example, in a 17 by 22 sheet the grain runs in the direction of the 17-inch side.
“100% cotton content, extra #1” paper has been made entirely of new fibers that have never been dyed or bleached. Paper marked “100% cotton content” may contain bleached fibers. Cotton content decreases in 25% steps over the three remaining grades. The 25% grade is comparable to sulphite #4 bond.
Grades run from 1 through 5, with 1 the best. Grades 3 and 5 are no longer produced. Most of the sulphite paper sold is #4.
Pocket Pal. A Graphic Arts Production Handbook.
International Paper Company. New editions are released regularly, the most
recent was August 1998.
Standard handy reference.
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Last revised: 16 May 2004.