A0 paper size
841 × 1189 mm
33.11 × 46.81 inches · 84.1 × 118.9 cm · aspect ratio 1:1.41
A0 size is 841 × 1189 mm. Those are the A0 dimensions a printer works to; the same sheet in centimetres, inches, points and pixels is below.
What A0 is for
A0 is defined, not derived: one square metre of area with sides in a 1:√2 ratio, which fixes it at 841 × 1189 mm and makes every other A size a halving of it. That definition is the reason paper weight is quoted in grams per square metre — a single A0 sheet of 80 gsm stock weighs exactly 80 grams, and an A4 sheet of the same paper weighs a sixteenth of that, 5 grams. Academic conference posters are the most common A0 job, and the usual mistake is designing one at screen resolution: an image that looks sharp in a slide deck is roughly 300 pixels wide on an A0 print.
A0 dimensions in every unit
| Unit | Width | Height |
|---|---|---|
| Millimetres | 841 mm | 1189 mm |
| Centimetres | 84.1 cm | 118.9 cm |
| Inches | 33.11 in | 46.81 in |
| Points (PostScript) | 2384 pt | 3370 pt |
A0 in pixels
Pixel dimensions depend entirely on the resolution you are working at — there is no single "pixel size" for a sheet of paper. A0 size in pixels has every resolution, with file sizes and canvas setup.
| Resolution | Pixels | Use |
|---|---|---|
| 72 DPI | 2384 × 3370 | Screen preview only — far too coarse to print |
| 150 DPI | 4967 × 7022 | Draft printing, internal documents |
| 300 DPI | 9933 × 14043 | The standard for commercial print |
| 600 DPI | 19866 × 28087 | 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 A0 relates to the rest of the series
A0 is A0 halved no times — it is the base of the series. 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.
A0 is defined as one square metre of area with sides in a 1:√2 ratio. Every other size in the series is derived from it by halving, which is why none of the dimensions are round numbers.
Against the sheet most people picture: one of these holds 16 A4 sheets.
Scaling to the next size up or down is a factor of √2 ≈ 1.414 on each edge, so enlarging A0 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 A0
The base of the A series, defined as one square metre of area with sides in a 1:√2 ratio. Every smaller A size is this one halved repeatedly.
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 |
|---|---|---|
| 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 |
| A4 | 210 × 297 mm | 8.27 × 11.69 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 A0 in mm?
841 × 1189 mm.
What size is A0 in inches?
33.11 × 46.81 inches.
What size is A0 in pixels?
There is no single answer — it depends on resolution. At the print standard of 300 DPI it is 9933 × 14043 pixels; at 72 DPI it is only 2384 × 3370.