Use GSM to compare paper weight across different paper categories. If a label gives a weight in pounds, read the paper category beside it, such as text, cover or bond. The number alone can be misleading: 80 lb text and 80 lb cover are different weights per unit of area. Neenah’s Paper 101 guide explains why those categories matter.
Keep sheet size, sheet count and thickness separate from the weight rating. Together, those details tell you much more than the biggest number on the wrapper.
Start with grams per square meter
GSM, also written g/m², means grams per square meter. It describes how much a square meter of that paper weighs. A 120 GSM sheet has more mass per equal area than an 80 GSM sheet, regardless of the size in which the paper is sold. Strathmore explains this comparison.
GSM is not the weight of the whole pack. Cutting a sheet into smaller pieces does not change its GSM, just as dividing a length of fabric does not change its material.
For a simple imaginary example, a sheet measuring half a meter by half a meter covers one-quarter of a square meter. At 120 GSM, that sheet would weigh about 30 grams. Its label would still say 120 GSM, not 30 GSM.
Read pounds together with the paper category
The US basis weight is the weight of 500 sheets at a standard reference size for that paper category. The reference size is not necessarily the size of the sheets in your packet.
Utah Valley University’s printing primer lists these common basic sizes:
- Bond and copy paper: 17 × 22 inches.
- Text paper: 25 × 38 inches.
- Cover paper: 20 × 26 inches.
Because the reference sheets differ in area, matching pound numbers do not establish matching paper weight per area. A packet marked 80 lb cover does not weigh 80 pounds, nor does an individual sheet. The label refers back to the standard 500-sheet calculation.
When a listing says only “80 lb,” look for the missing category or a GSM value. Avoid converting pounds to GSM with a single universal multiplier; the category is part of the calculation.
Compare two labels that both say 80 lb
Neenah’s CLASSIC Linen specification sheet gives a useful real example:
- 80 Text: 118 GSM.
- 80 Cover: 216 GSM.
The same pound number appears on both, but the cover stock has substantially more mass per equal area. The GSM figures make that difference clear immediately.
Our illustration uses those published figures in simplified sample labels. It is an explanation of the units, not a photograph of product packaging. For an actual order, read the manufacturer’s specification for the particular paper rather than assuming that every rounded conversion chart will agree exactly.
Check thickness separately
Paper thickness is called caliper. Strathmore’s glossary describes it in thousandths of an inch, also called mils. A specification may instead express thickness in millimeters.
GSM measures mass per area; caliper measures thickness. Do not read “200 GSM” as “0.2 mm.” Weight alone is not a complete description of how a paper will feel, bend or feed through a machine.
Other properties have their own terms. Opacity concerns how much light passes through a sheet, while surface finish describes its texture. Those matter when you want writing on the reverse to show through less, or need a particular drawing surface. Check those properties directly rather than expecting a weight rating to answer every question.
Match the paper to the job and equipment
For printing, check your exact printer’s approved paper types, sizes and weight limits, including the tray or feed slot you intend to use. Also check whether two-sided printing is supported for that stock.
An Epson paper-loading guide illustrates why: its limits differ between cassettes and the rear feed, and some thicker papers are excluded from double-sided printing. These are model-specific instructions, not limits for every printer.
For art or craft work, look for the intended medium and try a small sample. A heavier paper is not automatically a better paper; Strathmore notes that weight often reflects intended use rather than quality.
Before choosing, check five things: paper category, GSM, finished sheet size, thickness where relevant, and suitability for the task. That short list prevents the common mistake of choosing by pounds alone.
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