GSM Paper
Also known as: Grammage, Paper weight
What Is GSM Paper?
GSM (grams per square meter) is the standard measure of paper weight: how much one square meter of the paper weighs. One A0 sheet is exactly one square meter, so on 150 gsm paper it weighs 150 grams. Weights run from about 80 gsm for office paper to 400 gsm for thick business cards. GSM measures weight, not thickness.
US printers quote pounds instead, which depend on the paper grade. Heavier stock also changes the layout, from creased folds to a wider book spine, and CE.SDK’s page guides keep content clear of the trim and the spine.
What GSM Should You Use for Each Print Job?
Typical ranges by product. Match the weight to how the piece is handled: light enough to fold and mail, heavy enough to last.
| Used for | US weight | |
|---|---|---|
| 80 to 100 gsm | Copy paper, letters, forms | About 20 to 27 lb bond |
| 115 to 150 gsm | Flyers, leaflets, booklet pages | About 80 to 100 lb text |
| 170 to 200 gsm | Posters, menus, light covers | About 65 to 75 lb cover |
| 250 to 300 gsm | Postcards, invitations, covers | About 90 to 110 lb cover |
| 300 to 400 gsm | Business cards, greeting cards | About 110 to 150 lb cover |
How Do You Convert Pounds to GSM?
Multiply text weight by 1.48 and cover weight by 2.704. A pound weight is what 500 sheets weigh at a basis size, and cover stock is weighed on a smaller sheet than text, so the same number means a heavier paper. Bond, the grade for copy paper, converts at 3.76.
| Text | Cover | |
|---|---|---|
| 50 lb | 74 gsm | 135 gsm |
| 60 lb | 89 gsm | 162 gsm |
| 65 lb | 96 gsm | 176 gsm |
| 70 lb | 104 gsm | 189 gsm |
| 80 lb | 118 gsm | 216 gsm |
| 100 lb | 148 gsm | 270 gsm |
| 110 lb | 163 gsm | 297 gsm |
| 130 lb | 192 gsm | 352 gsm |
Is a Higher GSM Paper Thicker?
GSM is a good guide to thickness, not a measurement of it.
Usually, along with stiffness
Heavier paper is usually thicker and stiffer, meaning it resists bending more, but two 250 gsm stocks can still differ on both.
Uncoated paper is thicker at the same GSM
Coating and pressing compress the fibers, so a 150 gsm uncoated sheet can feel thicker than a 150 gsm gloss.
Points give the thickness directly
US printers quote card thickness in points, thousandths of an inch, so 14 pt card is 0.014 inches thick. Stocks sold at the same point size can differ by 80 gsm or more.
What Changes When You Choose a Heavier Paper?
Folds need creasing first
Heavier stock can crack along a fold, especially where dark ink crosses it, so printers crease it before folding.
Ink stops showing through
From around 160 gsm, a double-sided flyer stays clean on both sides. Below that, dark areas on one side can show on the other.
The book spine gets wider
Spine width comes from page weight and page count. A 100-page softcover on 130 gsm silk has a spine of about 7 mm, and about 9 mm on 170 gsm.
Booklet pages creep outward
In a stapled booklet, thicker paper pushes the inner pages out further, so the trim cuts closer to their content.
How Do You Plan a CE.SDK Design Around Paper Weight?
Set a safety inset
The safety inset keeps text and logos clear of the trim, since printers cut with a tolerance. Every inset defaults to 0, so set a value, and make it wider on thick booklets so text clears the creep.
Mark the spine and glue flaps
Exclusion areas mark regions that content must stay out of, such as a book spine or a glue flap on a box. Size the spine from your printer’s spine width for the chosen paper. Like the safety inset, exclusion areas stay out of the exported file.
Export one PDF for every weight
Flyers, cards, and other flat pieces print from the same PDF on any weight, so send the weight to the printer with the order. Book covers are the exception, since the spine changes with the paper.
Paper Weight in Print Shops and Photo Books
Weight options in a print shop
A web-to-print shop sells flyers on 130, 170, and 250 gsm. Customers design once in CE.SDK, pick the weight at checkout, and the same PDF goes to the printer.
Photo book covers that fit the spine
A photo book editor sizes the cover’s spine from the page count and paper weight, then marks it as an exclusion area, so cover photos stay off the spine.
FAQs
Most office and copy paper is 80 gsm, so an A4 sheet weighs 5 grams. In the US, copy paper is sold as 20 to 24 lb bond, about 75 to 90 gsm.
Most business cards are 300 to 400 gsm. 350 gsm is a common default, and 400 gsm or more gives a thicker, premium card.
There's no fixed line. Stock from around 250 gsm starts to feel like light card, and printers usually call it card when it's used for covers, postcards, and business cards.
Multiply the GSM by the sheet area in square meters, then by the number of sheets. An A6 postcard on 350 gsm weighs about 5.4 grams, which helps when you price postage for a mailing.
Not by itself. Color depends mostly on the finish: coated paper holds ink on its surface for stronger color, while uncoated paper absorbs more ink and prints softer.
Links
Documentation and references for this concept.
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