Quick answer
A4 is 210 × 297 mm (8.27 × 11.69 in). For a sharp print at 300 DPI it needs 2480 × 3508 pixels.
The A series is the international paper standard (ISO 216): each size is half of the one before, so two A4 sheets make an A3 and an A4 folded in half is an A5. North America uses its own sizes instead – Letter, Legal and Tabloid.
The pixel columns tell you how large an image must be to print sharply: 300 DPI for photos and print shops, 150 DPI for posters seen from a distance, 72 DPI for screen-only use.
ISO A paper sizes
| Size | mm | Inches | Pixels at 300 DPI | Pixels at 150 DPI | Pixels at 72 DPI |
|---|---|---|---|---|---|
| A0 | 841 × 1189 | 33.11 × 46.81 | 9933 × 14043 | 4967 × 7022 | 2384 × 3370 |
| A1 | 594 × 841 | 23.39 × 33.11 | 7016 × 9933 | 3508 × 4967 | 1684 × 2384 |
| A2 | 420 × 594 | 16.54 × 23.39 | 4961 × 7016 | 2480 × 3508 | 1191 × 1684 |
| A3 | 297 × 420 | 11.69 × 16.54 | 3508 × 4961 | 1754 × 2480 | 842 × 1191 |
| A4 | 210 × 297 | 8.27 × 11.69 | 2480 × 3508 | 1240 × 1754 | 595 × 842 |
| A5 | 148 × 210 | 5.83 × 8.27 | 1748 × 2480 | 874 × 1240 | 420 × 595 |
| A6 | 105 × 148 | 4.13 × 5.83 | 1240 × 1748 | 620 × 874 | 298 × 420 |
| A7 | 74 × 105 | 2.91 × 4.13 | 874 × 1240 | 437 × 620 | 210 × 298 |
| A8 | 52 × 74 | 2.05 × 2.91 | 614 × 874 | 307 × 437 | 147 × 210 |
| A9 | 37 × 52 | 1.46 × 2.05 | 437 × 614 | 219 × 307 | 105 × 147 |
| A10 | 26 × 37 | 1.02 × 1.46 | 307 × 437 | 154 × 219 | 74 × 105 |
North American paper sizes
| Size | Inches | mm | Pixels at 300 DPI | Pixels at 150 DPI |
|---|---|---|---|---|
| Letter | 8.5 × 11 | 216 × 279 | 2550 × 3300 | 1275 × 1650 |
| Legal | 8.5 × 14 | 216 × 356 | 2550 × 4200 | 1275 × 2100 |
| Tabloid | 11 × 17 | 279 × 432 | 3300 × 5100 | 1650 × 2550 |
| Executive | 7.25 × 10.5 | 184 × 267 | 2175 × 3150 | 1087 × 1575 |
| Half Letter | 5.5 × 8.5 | 140 × 216 | 1650 × 2550 | 825 × 1275 |
How to choose the right size for printing
- Check the pixel size of your image (right-click → Properties → Details in Windows).
- Compare it with the pixels at 300 DPI for the paper you want: if your image is at least that big, it will print sharp.
- If it is smaller, choose a smaller paper size, or accept 150–200 DPI for a poster seen from further away.
- Leave a few millimeters of margin – most home printers cannot print to the edge.
Questions
How many pixels is A4 at 300 DPI?
2480 × 3508 pixels (portrait).
Is A4 the same as US Letter?
No. A4 (210 × 297 mm) is slightly narrower and taller than US Letter (8.5 × 11 in, 216 × 279 mm).
What size is A3?
A3 is 297 × 420 mm (11.69 × 16.54 in) – twice the size of A4.