Paper Weight and GSM
Paper weight is measured in grams per square metre (gsm): the mass of a single one-metre-square sheet of that stock. It says nothing about size and everything about thickness and stiffness.
At a Glance
| Unit | Grams per square metre (gsm or g/m²) |
|---|---|
| Defined by | ISO 536 |
| What it measures | Mass of a 1 m² sheet, not thickness directly |
| Office copy paper | 80 gsm |
| Letterhead | 90 to 120 gsm |
| Card and covers | 200 to 350 gsm |
What GSM Actually Is
Take one square metre of a paper stock and weigh it. That weight in grams is its gsm. An 80 gsm sheet of A4 weighs 80 × 0.0625 = 5 grams, because A4 is one sixteenth of a square metre.
What Each Weight Feels Like
Newsprint runs 45 to 55 gsm. Standard copy and printer paper is 80 gsm. Letterhead and good inkjet paper is 90 to 120 gsm. Flyers that need to feel substantial are 130 to 170 gsm. Business cards, postcards and folder covers are 250 to 350 gsm. Anything above 350 gsm is usually called board.
GSM versus US Pound Weights
US paper is sold by the weight of a 500-sheet ream at a base size that differs by paper type, so “20 lb bond” and “50 lb text” can be the same 75 gsm sheet. GSM avoids that: it is the same number whatever the sheet size. To convert text-weight paper, multiply the pound figure by about 1.48; for cover stock, by about 2.70.
Thickness Is Related, Not Identical
Two sheets at the same gsm can differ in thickness if one is bulkier or more compressed. Uncoated and recycled stock tends to be thicker per gram than a coated gloss. Where thickness matters, a book spine, a business-card feel, check the caliper in microns as well as the gsm.
Frequently Asked Questions
What does gsm mean on paper?
Grams per square metre, the weight of a single one-metre-square sheet of that stock. Higher gsm means a heavier, usually stiffer sheet.
What gsm is normal printer paper?
80 gsm. It is the default for copiers and office printers worldwide.
What gsm should a business card be?
Between 300 and 400 gsm. Below 250 gsm a card feels flimsy; above 400 gsm many printers cannot feed it.
Is 100 gsm thicker than 80 gsm?
Usually, but not always. GSM is weight, not thickness. A bulky uncoated 90 gsm can feel thicker than a compressed coated 100 gsm.
✓ Details per the cited standards and the ISO catalogue. Last verified . Editorial Process →