Updated · Built and checked by the PlinzoTools team, formulas tested against published sources
Convert paper weight from pounds to GSM for any basis size.
203.08 g/m²
Equivalent Weight (always shown)
US paper suppliers rate paper weight in pounds -- but that figure only makes sense relative to a specific basis sheet size that varies by paper category (Bond, Text, Cover, and others each use a different standard size). GSM (grams per square meter) is the international, size-independent alternative. This converter turns a pound rating into GSM correctly, using the basis size your paper category actually applies.
Enter your paper's weight in pounds and select its basis size category: Bond (17×22in), Text (25×38in), Cover (20×26in), Index (25.5×30.5in), Bristol (22.5×28.5in), or Tag (24×36in). The result shows GSM, plus equivalent pound weights in Bond, Cover, and Index for easy cross-category comparison.
Factor = 1406.5 ÷ (Basis Length (in) × Basis Width (in))
GSM = Pounds × Factor
This is the inverse of the GSM-to-pounds formula -- multiplying by the same basis-size-dependent factor instead of dividing by it.
| Category | Basis Size | Typical Use |
|---|---|---|
| Bond | 17 × 22in | Letterhead, copy paper, writing paper |
| Text | 25 × 38in | Brochures, magazine interiors |
| Cover | 20 × 26in | Business cards, postcards, book covers |
| Index | 25.5 × 30.5in | Index cards, tabs, file folders |
| Bristol | 22.5 × 28.5in | Cardstock, presentation materials |
| Tag | 24 × 36in | Tags, heavy-duty labels |
Designers and print buyers working with an international supplier or printer who specifies stock in GSM, converting from a familiar US pound-based order spec. Useful for matching paper stock consistency across a project that spans US and international print vendors.
Always double-check which basis size category your pound rating belongs to -- selecting the wrong category (Bond vs. Cover, for example) produces a meaningfully wrong GSM result, since each category's basis sheet area is different.
Here are a few hypothetical stock specifications to show how the basis size changes the outcome.
Compare 20 lb Bond (about 75 GSM) with 100 lb Text (about 148 GSM). The much larger pound number belongs to a paper only about twice as heavy per square meter, because the Text basis sheet is much larger.
Print shops outside the US usually quote stock in GSM. Give them the converted figure and the category, for example: I normally order 80 lb Cover, which is about 216 GSM. They can then propose their closest available weight, which might be 210 or 220 GSM. Accept the nearest standard weight; nobody manufactures every possible GSM value.
The most common mistake is forgetting the category and assuming the default Bond basis. A card stock listed as 80 lb is nearly always 80 lb Cover; converting it as Bond would give around 301 GSM instead of about 216 GSM, which would be a big mismatch. Another mistake is treating the pound rating as the weight of a single sheet. It describes 500 sheets of the category's basis size, so it says nothing directly about the weight of a letter-size page.
The conversion is defined by area, so it ignores thickness, coating, and finish. Different mills round their pound numbers differently, and some specialty papers use their own conventions. Treat the GSM you get as a close equivalent and confirm the final choice with a sample. Some papers are also labeled with a pound rating that already includes a metric comparison, in which case the printed GSM is the more reliable figure.
20 lb Bond converts to approximately 75.24 GSM, using the Bond basis size (17in × 22in). Selecting a different basis category for the same "20 lb" figure gives a different GSM result.
GSM isn't inherently more accurate -- it's simply size-independent, so it avoids the basis-size ambiguity that makes comparing pound ratings across different paper categories confusing.
About 216.4 GSM using the Cover basis of 20 × 26 in.
Using the Bond factor of about 3.7621, 24 lb is about 90.3 GSM.
Yes. If they belong to different categories, their pound ratings are measured against different basis sheets, so identical GSM can appear as different pound numbers.
Generally yes. Suppliers sell standard weights, so round to the nearest available option and ask for a sample if the difference matters.
Reference: NIST Weights and Measures