A4 paper size
210 × 297 mm
8.27 × 11.69 inches · 21 × 29.7 cm · aspect ratio 1:1.41
A4 size is 210 × 297 mm. Those are the A4 dimensions a printer works to; the same sheet in centimetres, inches, points and pixels is below.
What A4 is for
A4 is the default sheet of paper for most of the world, and the size almost every document template, PDF and printer outside North America assumes. Its practical significance is what happens at the border with Letter: A4 is 6 mm narrower and 18 mm taller, so a document laid out for one is always slightly wrong on the other. Printers usually resolve this by scaling to fit, which shrinks the content by about 6% and quietly changes every measured dimension on the page — a real problem for anything printed to scale, and the reason architectural and legal documents specify their sheet size explicitly.
A4 dimensions in every unit
| Unit | Width | Height |
|---|---|---|
| Millimetres | 210 mm | 297 mm |
| Centimetres | 21 cm | 29.7 cm |
| Inches | 8.27 in | 11.69 in |
| Points (PostScript) | 595 pt | 842 pt |
A4 in pixels
Pixel dimensions depend entirely on the resolution you are working at — there is no single "pixel size" for a sheet of paper. A4 size in pixels has every resolution, with file sizes and canvas setup.
| Resolution | Pixels | Use |
|---|---|---|
| 72 DPI | 595 × 842 | Screen preview only — far too coarse to print |
| 150 DPI | 1240 × 1754 | Draft printing, internal documents |
| 300 DPI | 2480 × 3508 | The standard for commercial print |
| 600 DPI | 4961 × 7016 | Fine detail, line art, archival scanning |
Setting up a print document? Use 300 DPI and add 3 mm of bleed on every edge unless your printer specifies otherwise.
How A4 relates to the rest of the series
A4 is A0 halved 4 times. Halving a sheet across its longer side is what generates the next size down, and because the sides are in a 1:√2 ratio the proportions survive every fold — which is the entire reason the series exists.
That makes 16 sheets of A4 exactly one sheet of A0, with nothing left over. The area works out at 0.0625 m², since A0 is defined as one square metre.
Scaling to the next size up or down is a factor of √2 ≈ 1.414 on each edge, so enlarging A4 to the next size is 141% on a photocopier and reducing it is 71%. Those two numbers are on the preset buttons of most copiers for exactly this reason, and they are the same for every size in the series.
About A4
The default sheet of paper almost everywhere except North America. If you have ever printed anything outside the US or Canada, it was almost certainly A4.
Why A sizes halve so neatly
The A series is built on a 1:√2 ratio — approximately 1:1.414. That proportion has a unique property: cut the sheet in half across its long side and the two halves keep exactly the same proportions. This is why two A4 sheets make an A3, why scaling A4 artwork to A3 needs no cropping, and why photocopiers have a single "A4 → A3" button that just works.
Other ISO A series sizes
| Size | Millimetres | Inches |
|---|---|---|
| A0 | 841 × 1189 mm | 33.11 × 46.81 in |
| A1 | 594 × 841 mm | 23.39 × 33.11 in |
| A2 | 420 × 594 mm | 16.54 × 23.39 in |
| A3 | 297 × 420 mm | 11.69 × 16.54 in |
| A5 | 148 × 210 mm | 5.83 × 8.27 in |
| A6 | 105 × 148 mm | 4.13 × 5.83 in |
| A7 | 74 × 105 mm | 2.91 × 4.13 in |
| A8 | 52 × 74 mm | 2.05 × 2.91 in |
| A9 | 37 × 52 mm | 1.46 × 2.05 in |
| A10 | 26 × 37 mm | 1.02 × 1.46 in |
| Super A3 | 329 × 483 mm | 12.95 × 19.02 in |
Frequently asked questions
What size is A4 in mm?
210 × 297 mm.
What size is A4 in inches?
8.27 × 11.69 inches.
What size is A4 in pixels?
There is no single answer — it depends on resolution. At the print standard of 300 DPI it is 2480 × 3508 pixels; at 72 DPI it is only 595 × 842.