The surprising rule: bigger = fewer dpi
The key thought up front: the required resolution depends not only on the format, but on the viewing distance. A flyer sits 30 cm from your eyes — you can spot every pixel, so it needs a fine 300 dpi. A large poster is seen from five meters — where fine detail blurs anyway, so far fewer dpi suffice. That's why posters may be printed at lower resolution than business cards. The principle is the same as the relationship of DPI, PPI and resolution.
Resolution guide values by format
| Product | Viewing | dpi (guide) | Pixels (approx.) |
|---|---|---|---|
| A6 flyer (105 × 148 mm) | hand | 300 | 1240 × 1748 |
| A5 flyer (148 × 210 mm) | hand | 300 | 1748 × 2480 |
| A4 poster / notice | close | 300 | 2480 × 3508 |
| A2 poster | 1–2 m | 150–200 | ~2480 × 3500 (at 150) |
| A1 poster | 2–3 m | 120–150 | ~3500 × 4960 (at 150) |
| A0 / billboard | 3 m+ | 72–120 | depends on distance |
Note: even "only" 150 dpi demands enormous pixel counts at large formats. An A1 poster at 150 dpi needs about 3500 × 4960 pixels — a phone photo barely covers that, a web download (1000 px) never.
Why web images are almost always too small
The most common reason for rejected print data: images from the internet. A photo saved from a website is often only 800–1500 px — screen-fine, but too little for paper. And upscaling doesn't help: where there are no pixels, no software can invent them. Always get the original at full resolution (camera, photographer, image library at print size). Shrinking is no problem, enlarging is.
Vector always stays sharp
Text, logos, and flat areas belong — where possible — in the file as vector: they're razor-sharp at any size, from A6 flyer to A0 poster. Only photos are necessarily pixel-based and therefore need the resolution planning above. Embed logos as SVG, not as a small raster PNG.
Don't forget bleed and safety margin
As with every print product: pull the background into the bleed, keep important content within the safety margin. For large posters the values are bigger (often 3–5 mm bleed, 5–10 mm safety margin). The full explanation is in Bleed and trim explained.
The checklist before uploading
- Format and dpi matched to the viewing distance?
- Photos at sufficient resolution (original, not a web download)?
- Text/logo as vector, not a small pixel image?
- Bleed and safety margin set per the spec sheet?
- Color to spec (CMYK or RGB, see CMYK vs RGB)?
In short
- Viewing distance sets the dpi — bigger, farther = fewer dpi.
- Flyers 300 dpi, large posters 100–150 dpi.
- Web images are too small — use full-resolution originals.
- Vector for text/logos; plan bleed and safety margin.