Paper Weight Calculator (GSM)
By Santaji GadepatilinUpdated October 27, 2026
Paper thickness is described by GSM — grams per square metre. Knowing it lets you calculate the weight of a ream or a print job. This free paper weight calculator solves for whichever value you leave blank and shows the formula and steps.
How to use the paper weight calculator
Choose the paper size, enter the GSM and the number of sheets. The weight per sheet and total weight are calculated — useful for postage and shipping.
Paper weight formula
weight = GSM × sheet area × sheets
Example
A ream of A4 at 80 GSM: 80 × 0.06237 = 4.99 g per sheet → 2.49 kg per 500 sheets.
GSM guide
| GSM | Typical use |
|---|---|
| 60–70 | Newsprint, notebooks |
| 75–80 | Everyday office printer paper |
| 90–120 | Letterheads, quality documents |
| 130–170 | Flyers, brochures, posters |
| 200–250 | Brochure covers, light card |
| 300–350 | Business cards, postcards, invitations |
| 400+ | Premium business cards, packaging |
Paper sizes and areas
| Size | Dimensions | Area | Weight of 1 sheet at 80 gsm |
|---|---|---|---|
| A3 | 297 × 420 mm | 0.1247 m² | 9.98 g |
| A4 | 210 × 297 mm | 0.0624 m² | 4.99 g |
| A5 | 148 × 210 mm | 0.0311 m² | 2.49 g |
| US Letter | 216 × 279 mm | 0.0603 m² | 4.82 g |
| US Legal | 216 × 356 mm | 0.0769 m² | 6.15 g |
An A0 sheet is exactly 1 m², so a sheet of A0 at 80 gsm weighs 80 g. Each smaller A size is half the previous one.
GSM vs US paper weight (lb)
US paper is labelled by the weight of 500 sheets in its basic size, which differs by paper type:
| US weight | Approx. GSM |
|---|---|
| 20 lb bond | 75 |
| 24 lb bond | 90 |
| 80 lb text | 120 |
| 80 lb cover | 216 |
| 100 lb cover | 270 |
Postage
Postage often depends on weight. Ten A4 sheets at 80 gsm weigh about 50 g, plus about 5–10 g for a C4 envelope.
Frequently asked questions
What does GSM mean?
Grams per square metre — the weight of one square metre of the paper.
How much does a ream of A4 80 GSM weigh?
About 2.5 kg (500 sheets × 4.99 g).
What GSM is typical?
70–90 GSM for office paper, 120–170 for brochures and flyers, 250–350 for business cards.
How much does an A4 sheet of 80 gsm paper weigh?
About 5 g.
How much does a ream of A4 paper weigh?
500 sheets of 80 gsm A4 weigh about 2.5 kg.