A3 size in pixels
A3 is 297 × 420 mm. In pixels that is 3508 × 4961 at 300 DPI for print and 842 × 1191 at 72 DPI.
A3 is two A4 pages side by side, used for small posters, drawings and spreads. It measures 297 × 420 mm, or 11.69 × 16.54 in, with sides in the ratio 1 to √2 so that it halves into the next size down.
| Resolution | Pixels (portrait) | With 3 mm bleed | Megapixels | Uncompressed |
|---|---|---|---|---|
| 72 DPI | 842 × 1191 | 859 × 1208 | 1 | 2.9 MB |
| 96 DPI | 1123 × 1587 | 1145 × 1610 | 1.8 | 5.1 MB |
| 100 DPI | 1169 × 1654 | 1193 × 1677 | 1.9 | 5.5 MB |
| 150 DPI | 1754 × 2480 | 1789 × 2516 | 4.3 | 12 MB |
| 200 DPI | 2339 × 3307 | 2386 × 3354 | 7.7 | 22 MB |
| 240 DPI | 2806 × 3969 | 2863 × 4025 | 11 | 32 MB |
| 300 DPI | 3508 × 4961 | 3579 × 5031 | 17 | 50 MB |
| 400 DPI | 4677 × 6614 | 4772 × 6709 | 31 | 89 MB |
| 600 DPI | 7016 × 9921 | 7157 × 10063 | 70 | 199 MB |
| 1200 DPI | 14031 × 19843 | 14315 × 20126 | 278 | 797 MB |
Landscape is the same numbers the other way round. Pixels are rounded to the nearest whole pixel. The last column is 8-bit RGB before compression.
Which resolution to use for A3
For print that will be held and read, use 300 DPI: 3508 × 4961 pixels, 17 megapixels. A sheet this large is usually seen from further back, so 150 DPI (1754 × 2480 pixels) is often enough and a quarter of the file. For a screen, the DPI number does nothing; only the pixel size matters.
Will a photo fill it?
- A 12 megapixel phone photo (4000 × 3000 pixels), cropped to fill A3, prints at 242 DPI: fine from a step back, a little soft up close.
- A 24 megapixel camera photo (6000 × 4000 pixels), cropped to fill A3, prints at 342 DPI: sharp at any distance.
- A 48 megapixel photo (8000 × 6000 pixels), cropped to fill A3, prints at 484 DPI: sharp at any distance.