A3 paper size
A3 is part of the ISO A range (ISO 216). Commonly used for drawings, diagrams, small posters.
All units
| Unit | Width | Height |
|---|---|---|
| Millimetres | 297 | 420 |
| Centimetres | 29.7 | 42 |
| Inches | 11.693 | 16.535 |
| Points (PostScript) | 841.9 | 1190.6 |
Pixel dimensions by resolution
Pixels are not a property of the paper — they depend on the resolution you print at. Build the document at the size you will actually output.
| Resolution | Pixels (W × H) | Use for |
|---|---|---|
| 72 DPI | 842 × 1,191 | Screen and web only |
| 96 DPI | 1,123 × 1,587 | Windows screen default |
| 150 DPI | 1,754 × 2,480 | Draft and home printing |
| 300 DPI | 3,508 × 4,961 | Standard for commercial print and print-on-demand |
| 600 DPI | 7,016 × 9,921 | Fine art and high-detail line work |
300 DPI is the number you want in almost every case. Print-on-demand services, Etsy printables and commercial printers all expect it. Exporting at 72 DPI and enlarging does not add detail — it just prints the same pixels bigger and softer.
Compared with other sizes
Other ISO A sizes
| Size | mm | inches | px at 300 DPI |
|---|---|---|---|
| A0 | 841 × 1189 | 33.11 × 46.81 | 9,933 × 14,043 |
| A1 | 594 × 841 | 23.39 × 33.11 | 7,016 × 9,933 |
| A2 | 420 × 594 | 16.54 × 23.39 | 4,961 × 7,016 |
| A4 | 210 × 297 | 8.27 × 11.69 | 2,480 × 3,508 |
| A5 | 148 × 210 | 5.83 × 8.27 | 1,748 × 2,480 |
| A6 | 105 × 148 | 4.13 × 5.83 | 1,240 × 1,748 |
| A7 | 74 × 105 | 2.91 × 4.13 | 874 × 1,240 |
| A8 | 52 × 74 | 2.05 × 2.91 | 614 × 874 |
| A9 | 37 × 52 | 1.46 × 2.05 | 437 × 614 |
| A10 | 26 × 37 | 1.02 × 1.46 | 307 × 437 |
Common questions
What size is A3 in millimetres?
A3 is 297 × 420 mm.
What size is A3 in inches?
11.693 × 16.535 inches, which is 29.7 × 42 cm.
How many pixels is A3 at 300 DPI?
3,508 × 4,961 pixels. That is the canvas size to use for anything going to a commercial printer. For screen-only use, 72 DPI gives 842 × 1,191 px.
What is A3 used for?
Drawings, diagrams, small posters.
Why does A3 have that unusual aspect ratio?
Every ISO size has a 1:√2 ratio (about 1:1.414). Halving the long side gives the next size down with the same proportions, so artwork scales between sizes without leaving a margin or needing to be cropped.