GSM vs LB Paper: Complete Guide for Book Printing

Quick Summary

GSM (grams per square meter) is a universal measurement that stays consistent across all paper types, while LB (pound) weight varies by paper category and can be confusing. For most books, 60 LB text (90 GSM) is the safest choice.

Always get paper samples before committing to avoid costly mistakes, and remember that 80 LB text paper and 80 LB cover paper are completely different weights.

Ever step into a print shop and freeze when they ask, “What paper weight—80 GSM or 50 LB?”

Paper weights can be confusing, and mixing them up can mess with your whole book printing plan. Pick wrong and the pages feel flimsy, almost see‑through. Go the other way and you’re hauling around something that feels like a brick.

In this guide, as a professional book printing manufacturer, I’m going to explain gsm vs lb paper, so you actually know what to choose and why. 

What is GSM in Paper Weight?

GSM means “grams per square meter.”

Cut a sheet into a clean one‑meter square, roughly 3.3 feet by 3.3 feet, and GSM is simply how much that piece would weigh.

What’s nice about GSM? It stays the same no matter the paper.

A 100 GSM sheet always weighs 100 grams per square meter, whether you’re holding plain copy paper, thick cardstock, or anything in between.

Here’s what different GSM weights feel like:

• 60-80 GSM: Standard copy paper (what’s in your printer right now)
• 90-120 GSM: Premium letterhead or magazine pages
• 130-170 GSM: Lightweight cardstock or heavy brochures
• 200-300 GSM: Business cards or book covers
• 350+ GSM: Premium packaging or luxury invitations

Understanding LB (Pound) Paper Weight

LB, or pound weight, comes from how much 500 sheets weigh at their “basis size.”

That basis size is the big, uncut sheet manufacturers start with. 

But here’s the kicker: Different types of paper have different basis sizes.

For example:

• Bond paper: 17″ × 22″
• Text paper: 25″ × 38″
• Cover paper: 20″ × 26″

So 80 LB text paper and 80 LB cover paper are not the same weight at all.

Totally different. Yeah, confusing.

GSM vs LB Paper: Key Differences

Let me break down the main differences:

GSM (Metric System)

• Universal measurement
• Always consistent
• Used globally
• Easier to compare different papers

LB (Imperial System)

• US-based measurement
• Varies by paper type
• Can be confusing
• Requires knowing the paper category

The bottom line? GSM is like using meters instead of feet – it just makes more sense once you get used to it.

GSM vs LB Paper Conversion Chart

Here’s a handy conversion chart I use all the time:

Text/Book Paper

• 50 LB Text = 75 GSM
• 60 LB Text = 90 GSM
• 70 LB Text = 105 GSM
• 80 LB Text = 120 GSM
• 100 LB Text = 150 GSM

Cover/Card Stock

• 65 LB Cover = 175 GSM
• 80 LB Cover = 215 GSM
• 100 LB Cover = 270 GSM
• 110 LB Cover = 300 GSM
• 130 LB Cover = 350 GSM

Pro Tip: Screenshot this chart on your phone. You’ll thank me later when you’re at the print shop.

Choosing the Right Paper Weight for Book Printing

Now for the million-dollar question: What weight should YOU use for your book?

Here’s what I recommend:

For Book Interior Pages

Mass Market Paperbacks: 50-60 LB Text (75-90 GSM)

• Lightweight and economical
• Perfect for novels with text-only content
• Keeps shipping costs down

Trade Paperbacks: 60-70 LB Text (90-105 GSM)

• Industry standard for quality books
• Good opacity (less show-through)
• Nice hand-feel without being heavy

Premium Books/Textbooks: 70-80 LB Text (105-120 GSM)

• Excellent for books with images
• Minimal show-through
• Feels substantial and high-quality

For Book Covers

Softcover/Paperback: 10pt-12pt C1S (250-300 GSM)

• Standard for most paperbacks
• Durable but flexible
• Takes printing well

Hardcover Dust Jackets: 80-100 LB Text (120-150 GSM)

• Lighter weight for wrapping
• Usually has a glossy or matte coating

Paper Thickness vs Paper Weight

Here’s something that trips people up:

Weight and thickness aren’t always directly related.

Two papers with the same weight can have different thicknesses because of:

• Fiber density: How tightly packed the fibers are
• Calendering: How much the paper is compressed during manufacturing
• Coatings: Added layers that affect thickness

This is why you’ll sometimes see paper thickness measured in “points” (1 point = 0.001 inches) alongside weight measurements.

Common Paper Weight Mistakes in Book Printing

I’ve seen these mistakes cost people thousands:

Mistake #1: Using office paper weight for books
Regular 20 LB bond (75 GSM) copy paper is TOO THIN for book pages. You’ll get serious show-through.

Mistake #2: Mixing up text and cover weights
Remember: 80 LB text ≠ 80 LB cover. Always specify which type you mean.

Mistake #3: Going too heavy
Thicker isn’t always better. A 400-page novel on 80 LB text would be massive and expensive to ship.

Mistake #4: Ignoring grain direction
Paper grain affects how pages turn. Always specify grain parallel to the spine.

Cost Implications of Different Paper Weights

Let’s talk money.

Paper typically accounts for 30-40% of your printing costs. Here’s how weight affects pricing:

• Lighter paper = Lower material cost + lower shipping
• Heavier paper = Higher material cost + higher shipping
• Sweet spot: 60 LB text (90 GSM) for most books

But here’s the thing: Sometimes paying 10% more for better paper can make your book feel 50% more premium.

International Paper Weight Standards

Working with international printers? You NEED to know this:

US Printers: Usually speak in LB
European Printers: Always use GSM
Asian Printers: Typically use GSM

When in doubt, always provide BOTH measurements. Say something like: “I want 60 LB text (90 GSM) for the interior pages.”

How to Test Paper Weights

Want to feel the difference yourself? Here’s what I do:

1. Order sample packs from your printer
2. Print the same page on different weights
3. Do the flip test: See how pages feel when turning
4. Check opacity: Hold pages up to light
5. Calculate spine width: Heavier paper = thicker book

Most printers will send samples for free or cheap. It’s worth the few bucks to get it right.

Environmental Considerations

Something to think about:

Heavier paper = more trees + more transportation emissions.

If you’re eco-conscious, consider:

• Using the minimum weight that works
• Choosing recycled paper options
• Printing locally to reduce shipping

Many 60 LB (90 GSM) recycled papers perform just as well as virgin 70 LB (105 GSM).

Digital vs Offset Printing Paper Weights

The printing method affects your paper choices:

Digital Printing:

• Limited to certain weights
• Usually maxes out at 100 LB text
• Better for short runs

Offset Printing:

• Handles any weight
• More paper options
• Better for 1000+ copies

Ask your printer about their equipment limitations BEFORE choosing paper.

Paper Weight Standards by Genre

Different book types have unofficial standards:

Fiction/Novels: 50-60 LB text (75-90 GSM)
Non-fiction: 60-70 LB text (90-105 GSM)
Photography books: 80-100 LB text (120-150 GSM)
Children’s books: 70-80 LB text or heavier (105-120 GSM)
Cookbooks: 70-80 LB text (105-120 GSM)

These aren’t rules, just starting points based on reader expectations.

Conclusion

Understanding gsm vs lb paper measurements doesn’t have to be complicated.

Remember:

• GSM is consistent and universal
• LB varies by paper type
• For most books, 60 LB text (90 GSM) is your safest bet
• Always get samples before committing

Pick the right paper weight and your book stops looking homemade and starts feeling legit.

Take a little time to choose well, and both your readers and your wallet will thank you.

You’re set to pick paper weights for your next book without second‑guessing.

Walk into the print shop with confidence now. You’ve got it.