A3 paper size
297 × 420 mm
11.69 × 16.54 inches · 29.7 × 42 cm · aspect ratio 1:1.41
A3 in every unit
| Unit | Width | Height |
|---|---|---|
| Millimetres | 297 mm | 420 mm |
| Centimetres | 29.7 cm | 42 cm |
| Inches | 11.69 in | 16.54 in |
| Points (PostScript) | 842 pt | 1191 pt |
A3 in pixels
Pixel dimensions depend entirely on the resolution you are working at — there is no single "pixel size" for a sheet of paper.
| Resolution | Pixels | Use |
|---|---|---|
| 72 DPI | 842 × 1191 | Screen preview only — far too coarse to print |
| 150 DPI | 1754 × 2480 | Draft printing, internal documents |
| 300 DPI | 3508 × 4961 | The standard for commercial print |
| 600 DPI | 7016 × 9921 | 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.
About A3
Exactly two A4 sheets side by side. The largest size most office printers handle, and the standard for spreadsheets, drawings and small posters.
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 |
| 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 |
Frequently asked questions
What size is A3 in mm?
297 × 420 mm.
What size is A3 in inches?
11.69 × 16.54 inches.
What size is A3 in pixels?
There is no single answer — it depends on resolution. At the print standard of 300 DPI it is 3508 × 4961 pixels; at 72 DPI it is only 842 × 1191.