Paper Weight Calculator — Grammage, Basis Weight & Sheet Weight
This paper weight calculator helps you determine the weight of paper sheets of any size. Whether you need to find out how much a ream of printer paper weighs for shipping, or convert between grammage (g/m²) and US basis weight (lbs), this tool has you covered.
What is Grammage (GSM)?
Grammage is the internationally recognized measure of paper weight, expressed as grams per square meter (g/m²), often abbreviated as gsm. It tells you how much one square meter of the paper weighs.
- 60–70 g/m² — lightweight paper (newspapers, flyers)
- 75–90 g/m² — standard office paper (most copy paper is 80 gsm)
- 90–120 g/m² — presentation paper, heavier brochures
- 120–170 g/m² — photo paper, card stock
- 170–350 g/m² — cover stock, business cards, postcards
- 350+ g/m² — rigid card, invitations
What is Basis Weight?
The basis weight is the US customary measure of paper weight. It is the weight in pounds of 500 sheets (one ream) of a paper's parent sheet size. Because different paper categories use different parent sheet sizes, the same physical paper can have different basis weights depending on the category:
| Paper Type | Parent Sheet Size | GSM = Basis × … |
|---|---|---|
| Bond / Writing / Ledger | 17" × 22" | × 3.76 |
| Text / Book / Offset | 25" × 38" | × 1.48 |
| Cover / Card | 20" × 26" | × 2.70 |
| Index / Postcard | 25.5" × 30.5" | × 1.81 |
| Tag / Newsprint | 24" × 36" | × 1.63 |
How to Calculate Paper Weight
The formula is simple:
Weight of a sheet = Grammage (g/m²) × Area of the sheet (m²)
For example, a standard A4 sheet (210 mm × 297 mm = 0.0623 m²) of 80 g/m² copy paper weighs:
80 × 0.0623 = 4.98 grams
A ream of 500 sheets therefore weighs approximately 2.49 kg — consistent with the marked weight on most office paper packages.
Common Paper Sizes
| Size | Dimensions | Area (m²) |
|---|---|---|
| A4 | 210 × 297 mm | 0.0624 |
| A3 | 297 × 420 mm | 0.1247 |
| A5 | 148 × 210 mm | 0.0311 |
| B5 | 176 × 250 mm | 0.0440 |
| Letter | 8.5 × 11 in | 0.0603 |
| Legal | 8.5 × 14 in | 0.0768 |
| Tabloid | 11 × 17 in | 0.1206 |
Frequently Asked Questions
How much does a single sheet of 80 g/m² A4 paper weigh?
Approximately 4.98 grams (0.18 oz). A 500-sheet ream weighs about 2.49 kg (5.5 lbs).
What is the most common paper weight for office printing?
80 g/m² (or 20 lb bond in US notation) is the universal standard for everyday copy and print paper.
Why does the same paper have different basis weights for different paper types?
Because each paper category uses a different parent sheet size for the ream measurement. A sheet of 80 gsm text paper would be labelled 54 lb text, whereas 80 gsm bond paper would be labelled about 21 lb bond.
How do I convert basis weight to gsm?
Multiply the basis weight by the conversion factor for the paper type. For bond paper: gsm = basis weight × 3.76. Use our calculator above to do this automatically.
Does grammage affect paper thickness?
Not directly — thickness also depends on the paper manufacturing process and fiber density. Two papers can have the same gsm but different thicknesses (caliper).