Paper Size Chart
A and B series sizes in millimeters and inches, US Letter and ANSI sizes, and how they compare.
A4 is 210 × 297 mm, or 8.27 × 11.69 inches. US Letter is 216 × 279 mm, or 8.5 × 11 inches, so Letter is 6 mm wider and 18 mm shorter than A4 and the two are not interchangeable.
By Piero Nanni · Last checked
Matching rows are highlighted in the tables below.
The A series is built on one idea: every sheet has an aspect ratio of 1:√2, so cutting it in half across the long side produces the next size down at the same ratio. A0 is defined as the sheet of that ratio with an area of exactly one square meter, and every other size follows by halving. That is why A4 is a quarter the area of A2 and why scaling A4 artwork to A3 needs no cropping.
North America uses a different family with no such property. Letter is 8.5 × 11 inches, chosen by convention rather than derivation, and halving it gives 5.5 × 8.5, which is a different shape. Printing an A4 document on Letter loses 18 mm from the bottom or forces a scale to 94 percent, and printing Letter on A4 leaves an uneven margin. Set the page size before writing, not at the printer.
A series
Each size is the previous one halved across its longer side. Dimensions are width × height in portrait.
| Size | Millimeters | Inches | Typical use |
|---|---|---|---|
| A0 | 841 × 1189 | 33.1 × 46.8 | Posters, technical drawings |
| A1 | 594 × 841 | 23.4 × 33.1 | Posters, flip charts |
| A2 | 420 × 594 | 16.5 × 23.4 | Drawings, large prints |
| A3 | 297 × 420 | 11.7 × 16.5 | Spreadsheets, small posters |
| A4 | 210 × 297 | 8.3 × 11.7 | Standard document size |
| A5 | 148 × 210 | 5.8 × 8.3 | Notebooks, flyers |
| A6 | 105 × 148 | 4.1 × 5.8 | Postcards |
| A7 | 74 × 105 | 2.9 × 4.1 | Tickets, small cards |
| A8 | 52 × 74 | 2.0 × 2.9 | Playing cards, labels |
B series
B sizes sit between the A sizes, and are used where A is slightly too small. B5 is a common book size.
| Size | Millimeters | Inches | Typical 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 |
| B3 | 353 × 500 | 13.9 × 19.7 | Posters, drawings |
| B4 | 250 × 353 | 9.8 × 13.9 | Books, newspapers |
| B5 | 176 × 250 | 6.9 × 9.8 | Books, magazines |
| B6 | 125 × 176 | 4.9 × 6.9 | Small books |
US and ANSI sizes
| Size | Inches | Millimeters | Closest A size |
|---|---|---|---|
| Half Letter | 5.5 × 8.5 | 140 × 216 | A5 (148 × 210) |
| Executive | 7.25 × 10.5 | 184 × 267 | A4 (210 × 297) |
| Letter / ANSI A | 8.5 × 11 | 216 × 279 | A4 (210 × 297) |
| Legal | 8.5 × 14 | 216 × 356 | No close equivalent |
| Tabloid / ANSI B | 11 × 17 | 279 × 432 | A3 (297 × 420) |
| ANSI C | 17 × 22 | 432 × 559 | A2 (420 × 594) |
| ANSI D | 22 × 34 | 559 × 864 | A1 (594 × 841) |
| ANSI E | 34 × 44 | 864 × 1118 | A0 (841 × 1189) |
Why A sizes halve so neatly
A sheet with sides in the ratio 1:√2 keeps that ratio when halved, because halving the long side divides it by two while the ratio only needs it divided by √2 twice. It is the only aspect ratio with this property, which is why the ISO 216 standard adopted it in 1975 on the basis of a German standard from 1922.
The practical consequence is that scaling between A sizes is a single number and never distorts. A4 to A3 is 141 percent, A3 to A4 is 71 percent, and those two figures cover almost all office copying. Letter to Tabloid needs 129 percent and still crops, because the shapes differ.
Printing A4 content on Letter and back
A4 is 18 mm taller and 6 mm narrower than Letter. Printing A4 at full size on Letter cuts 18 mm off the bottom; scaling to fit uses about 94 percent and shrinks the type. Going the other way, Letter on A4 leaves a 18 mm gap at the bottom and clips 6 mm at the sides at full size.
For anything that will cross the Atlantic, set generous margins, at least 20 mm all round, and the same document will print acceptably on both. Documents laid out to the edge of one format never survive the other.
Envelope sizes that match
A C series exists for envelopes, sized so the matching A sheet slides in unfolded: C4 takes A4 flat, C5 takes A4 folded once, and C6 takes A4 folded twice. DL, the long business envelope at 110 × 220 mm, takes A4 folded in three.
The US equivalents are the number series: a #10 envelope, 4.125 × 9.5 inches, takes Letter folded in three, and is the closest counterpart to DL though it is 5 mm shorter and 5 mm taller.
Frequently Asked Questions
What size is A4 in inches?
A4 is 8.27 × 11.69 inches, or 210 × 297 millimeters.
Is A4 the same as Letter?
No. Letter is 216 × 279 mm, so it is 6 mm wider and 18 mm shorter than A4. They are not interchangeable.
What size is A3?
A3 is 297 × 420 mm, or 11.7 × 16.5 inches, exactly twice the area of A4.
How do I scale A4 to A3?
Enlarge to 141 percent. Going from A3 to A4 is a 71 percent reduction.
What is the A0 size?
A0 is 841 × 1189 mm, defined as the 1:√2 sheet with an area of exactly one square meter.