Print quality
What resolution do photos need for printing?
Resolution advice is usually written for professional printers and full of numbers nobody needs. For a family photo book, one rule covers it: a photo needs about 1,600 pixels on its long side to fill a page sharply. Every phone made in the last ten years takes photos far larger than that.
Pixels, not megabytes or dpi
A digital photo is a grid of dots. How many dots it has, across and down, decides how large it can be printed before the dots start to show. "Dpi" is just how tightly those dots are packed on the paper.
Printers quote 300 dots per inch as ideal. That figure is for things read at arm's length under a magnifier. A photo in a book, held at reading distance, looks sharp at about half that.
How big can a photo print?
| Long side of the photo | Prints sharply up to | Where it usually comes from |
|---|---|---|
| 4,000 pixels | Much larger than a page | A phone camera, straight from the camera roll |
| 2,000 pixels | A full page (21 × 28 cm) | A good scan, or an HD copy from a chat app |
| 1,600 pixels | A full page, just | A standard copy from a chat app |
| 1,000 pixels | About half a page | A copy saved from social media |
| 500 pixels | A few centimetres | A thumbnail or a screenshot of a photo |
What Paper Chain does
- Photos are prepared at up to 2,800 pixels on the long side, which is more than a full page needs.
- Anything under 1,600 pixels is flagged as soon as it's added, to the person adding it and to the organiser.
- A small photo is printed smaller rather than stretched, so it stays crisp.
- Before you order, the review screen tells you how many photos are too small.
The things that matter more than pixels
A sharp twelve-megapixel photo taken in a dark room will still print grainy. Light matters more than resolution.
- Daylight. Photos taken near a window or outdoors print best.
- A steady hand. Blur from a moving phone can't be fixed by more pixels.
- No heavy filters. Strong filters and digital zoom both throw detail away.
If a photo matters and it's small, ask whoever took it to add the original themselves. See why chat-app photos print blurry.