GSM to LB: Paper Weight Conversion

GSM to LB. If you are thinking of printing something, such as a book or card, you may have seen two notations, “GSM” and “LB,” as units representing the thickness of paper. To be honest, this is confusing. Some say use “200 gsm,” while others say “80 lb,” so they don’t even know if they point to the same thing.

Here’s the good news: once you understand the basics, it’s actually simple. This guide will actually clear it.

1. What is GSM?

GSM stands for Grams per Square Meter. And think of it this way: take a piece of paper that’s 1 meter by 1 meter, weigh it, and that weight in grams is the GSM.

This is a standard unit of measurement used almost anywhere in the world except North America. Therefore, if you order from Asia, Europe and most other regions, it will be written in GSM.

Simple rule: The higher the GSM, the heavier and thicker the paper. That’s all.

2. What is LB (Pounds)?

LB (or lb or #) is how North America measures paper weight. Instead of measuring one sheet, they measure a whole ream of 500 sheets in their original, uncut size.

Note that the standard size varies depending on the type of paper. In other words, even if both are written as “80 lb,” the weight varies between 80 lb of cover paper and 80 lb of body paper. It’s pretty cool, isn’t it? Yes, we also know well.

For example:

80 lb cover: 500 sheets of 20″ × 26″ paper = 80 pounds
80 lb text: 500 sheets of 25″ × 38″ paper = 80 pounds

The cover paper is actually heavier in your hands because it starts as a bigger sheet. This is why you can’t just compare numbers and you have to know the type too.

3. Quick Conversion Formula

Don’t stress. Just use these simple formulas:

Converting GSM to LB:

Text paper: GSM × 0.676 = LB text
Cover paper: GSM × 0.369 = LB cover

Converting LB to GSM:

Text paper: LB × 1.48 = GSM
Cover paper: LB × 2.708 = GSM

Example: If someone says they want 150 gsm for their book interior, that’s 150 × 0.676 = about 101 lb text paper.

4. Common Paper Weight Chart

Here’s what you’ll see most often:

For Book Interiors (Text Weight):

80 gsm = 54 lb text (thin, lightweight)
100 gsm = 68 lb text (standard choice)
128 gsm = 87 lb text (thicker, premium feel)
157 gsm = 106 lb text (really thick, luxury books)

For Covers & Cards (Cover Weight):

200 gsm = 74 lb cover (thin card)
250 gsm = 92 lb cover (standard card deck)
300 gsm = 111 lb cover (premium, stiff card)

5. Which Weight Should You Actually Use?

This is the real question people ask.

For a book:

Interior pages: stick with 80-100 gsm (lightweight, saves money)
Hardcover jacket: 200-250 gsm (nice and sturdy)

For trading cards or card decks:

Use 250+ gsm minimum or they’ll feel cheap and bend easily

For postcards or flyers:

200-250 gsm is perfect, stiff enough to handle mail, not too expensive

For packaging boxes:

Depends on the size, but usually 200+ gsm

The rule is simple: the smaller the item, the heavier the paper should be. A book’s interior can be light. But a postcard needs to survive the mail, so it needs to be heavier.

6. GSM vs LB: Which One Should You Use?

Use whatever your printer or supplier uses.

If you’re ordering from China or Asia, they’ll work in GSM. If you’re ordering from a North American supplier, they want LB. Just convert using the formulas above and you’re good.

Pro tip: When you’re ready to order, just tell your printer what you want. Say something like: “I want 100 gsm for the interior and 250 gsm for the cover.” They’ll take care of the rest and might even suggest something better based on your project.

7. Common Mistakes People Make

Mistake #1: Thinking all “80 lb” papers are the same. They’re not. 80 lb cover ≠ 80 lb text.

Mistake #2: Choosing paper weight based only on price. Cheap, thin paper can ruin a beautiful design. Don’t save $50 and lose $500 in quality.

Mistake #3: Not ordering samples first. Paper feels different in your hands. Always order a sample pack and compare weights before committing to a big order.

Ready to Print?

So what to do next? Think about your project, choose a weight from the chart above that matches or ask yourself (is this a small card or a big book?), and then order samples.

We send paper sample books. That way, you can feel the actual paper, see the colors, and make sure it’s exactly what you want. No surprises on delivery day.

If you’re still not sure which weight to choose, just tell us about your project. Our team can recommend the perfect paper in about 5 minutes.

If you want to get started, you can contact us at China Book Printer and grab a sample pack or request a quote. We’ll help you pick the right paper weight for your project and make sure it looks amazing.

Do you have questions? Just reach out. We’re here to help.