Paper Sizes Chart (mm & inches)
Last updated: 2026-10-15
Whether you are printing a ruler, laying out a document, or just wondering why a sheet of paper is the size it is, the numbers below are the exact, standards-based dimensions. All millimetre values are the official ISO 216 and US sizes; inch values are exact conversions (1 inch = 25.4 mm).
Where paper sizes come from
Modern paper sizes come from Germany. The German Institute for Standardization published the rule in 1922, and it later became the international standard ISO 216. It answered two practical problems: cutting sheets from a larger stock wasted a lot of offcuts, and sheets of different sizes did not share a proportion, so anything rescaled had to be laid out again.
The ISO 216 approach sets one base size, A0, at an area of exactly 1 m², then halves it again and again. Because the side ratio is fixed at 1 to the square root of 2, a sheet cut in half keeps the same shape, so A0 down to A10 all share one proportion.
That fixed ratio is why an A4 document reprints on A3 without any layout damage: the page grows, the design does not distort.
ISO A series (the world standard)
The A series is based on a single elegant rule: every size has an aspect ratio of √2 : 1 (≈ 1.4142), so folding a sheet in half gives the next size with the same proportions. A4 (210 × 297 mm) is the everyday sheet; A0 has an area of exactly 1 m².
| Size | mm (W × H) | inches (W × H) | Use |
|---|---|---|---|
| A0 | 841 × 1189 | 33.1 × 46.8 | Posters, wall charts |
| A1 | 594 × 841 | 23.4 × 33.1 | Technical drawings |
| A2 | 420 × 594 | 16.5 × 23.4 | Posters, maps |
| A3 | 297 × 420 | 11.69 × 16.54 | Charts, small posters |
| A4 | 210 × 297 | 8.27 × 11.69 | Letters, printer default |
| A5 | 148 × 210 | 5.83 × 8.27 | Notebooks, booklets |
| A6 | 105 × 148 | 4.13 × 5.83 | Postcards |
| A7 | 74 × 105 | 2.91 × 4.13 | Notes, cards |
| A8 | 52 × 74 | 2.05 × 2.91 | Small cards |
| A9 | 37 × 52 | 1.46 × 2.05 | Stamp-sized |
| A10 | 26 × 37 | 1.02 × 1.46 | Smallest ISO card |
A4 is the default sheet for offices and schools. A3 is twice the area of A4 and takes drawings and posters. A5 is the usual notebook and booklet size, and A6 is the postcard size.
ISO B series (less common, used for books & passports)
The B series sits between the A sizes (B4 is between A3 and A4) and is used for posters, books, and passports. Same √2 aspect ratio.
| Size | mm (W × H) | inches (W × H) | Use |
|---|---|---|---|
| B0 | 1000 × 1414 | 39.4 × 55.7 | Large posters |
| B1 | 707 × 1000 | 27.8 × 39.4 | Posters |
| B2 | 500 × 707 | 19.7 × 27.8 | Posters, calendars |
| B3 | 353 × 500 | 13.9 × 19.7 | Books, magazines |
| B4 | 250 × 353 | 9.84 × 13.9 | Books, newspapers |
| B5 | 176 × 250 | 6.93 × 9.84 | Books, journals |
| B6 | 125 × 176 | 4.92 × 6.93 | Books, passports |
B5 turns up most often in books, journals and planners. It is larger than A5 and smaller than A4, a middle ground between comfortable typesetting and something you can still carry.
Envelope sizes (the C series)
Envelopes use the C series, sized so each one holds the matching A sheet.
| Size | mm (W × H) | inches (W × H) | Holds |
|---|---|---|---|
| C4 | 229 × 324 | 9.02 × 12.76 | An A4 sheet, unfolded |
| C5 | 162 × 229 | 6.38 × 9.02 | An A4 sheet folded once |
| C6 | 114 × 162 | 4.49 × 6.38 | An A4 sheet folded twice |
Formal documents usually travel in a C4, business correspondence in a C5, cards and notes in a C6.
US & Canadian sizes (ANSI)
The US does not use ISO paper. Letter and Legal are the everyday sizes; note they are not √2-shaped, which is why a US sheet never folds neatly into the next size.
| Size | mm (W × H) | inches (W × H) | Use |
|---|---|---|---|
| Letter | 215.9 × 279.4 | 8.5 × 11 | Everyday US sheet |
| Legal | 215.9 × 355.6 | 8.5 × 14 | Contracts, court filings |
| Ledger / Tabloid | 279.4 × 431.8 | 11 × 17 | Spreads, charts |
| Executive | 184.2 × 266.7 | 7.25 × 10.5 | Letters, memos |
Letter is the US default, holding the place A4 has everywhere else. Legal runs 3 inches longer than Letter and is used for contracts and court documents. Ledger, the same as Tabloid, is twice the area of Letter and usually sits landscape.
The big difference between Letter and A4 is 6 mm of width and 18 mm of length. A document laid out for one will have its margins shift when printed on the other, which is the most common problem when files travel between countries.
Business card sizes
Business cards sit outside ISO 216, so each country sets its own.
| Region | Size |
|---|---|
| United States | 3.5 × 2 in (88.9 × 50.8 mm) |
| Europe | 85 × 55 mm (3.35 × 2.17 in) |
| China (common) | 90 × 54 mm (3.54 × 2.13 in) |
The US card is the one most print shops quote by default. Confirm the exact size with your printer before ordering, because bleed and trim are both set from it.
Which size should I design for?
- Printing a ruler at home? Use Letter in the US and Canada, or A4 almost everywhere else. The printable ruler is laid out for both.
- Documents and reports? Letter in the US, A4 worldwide.
- Posters or signs? A2–A0, or B-series for a slightly larger area at the same step.
- Mailing a document? Work backwards from the C envelope, for example A4 folded once into a C5.
Then check the region. The US and Canada run on Letter and Legal; everyone else runs on the A series. When sending files across borders, confirm which size the other party prints on first.
Telling sheets apart without a ruler
Hold the unknown sheet against a sheet of Letter paper. An A4 sheet will fall short along the short edge (210 mm against Letter's 215.9 mm) and stick out along the long edge (297 mm against Letter's 279.4 mm), by a few millimetres each way, which is easy to see side by side.
When you need numbers rather than a comparison, use the online ruler. Calibrate it against a bank card first, then measure the width and length and match them to the table above. A US bank card is fixed at 85.60 mm (3.37 in) wide by ISO/IEC 7810, the same in every country, so it makes a reliable reference.
Two more stand-ins if nothing else is handy: a US banknote is 6.14 × 2.61 in, and a quarter is 0.955 in across.
Print tip
When you print, always choose 100% / “Actual size” and turn off “Fit to page”. Scaling the page changes every dimension above, so a “true size” ruler printed with fit-to-page would no longer measure correctly.
Frequently asked questions
How big is A4?
210 × 297 mm, which is 8.27 × 11.69 in.
Is A4 the same as Letter?
No. Letter is 8.5 × 11 in, wider and shorter than A4.
How do A3 and A4 relate?
A3 has twice the area of A4. Two A4 sheets side by side make one A3.
Is B5 bigger or smaller than A4?
Smaller. B5 is 176 × 250 mm against 210 × 297 mm for A4.
What size is a business card?
3.5 × 2 in in the US, 85 × 55 mm in Europe, and 90 × 54 mm in China.
Sources
- ISO 216 (A, B, C series): ISO 216
- US sizes (Letter, Legal): ANSI/ASME Y14.1
- Passports / ID-3: ICAO Doc 9303 and ISO/IEC 7810