You often hear that prints need 300 pixels per inch. That is true for a photo you hold in your hand, but a poster on a wall is seen from much further away, and your eye cannot see fine detail at a distance. A big print can have far fewer pixels per inch and still look sharp where people actually stand.
The rule: pixels per inch and viewing distance
A person with good eyesight can tell apart details that are about one minute of arc wide. Turned into print terms, that gives a simple formula:
Pixels per inch needed ≈ 3,438 ÷ viewing distance in inches
This is the level where individual pixels disappear for most people. Below it the picture is not suddenly bad, just a little softer than it could be.
| Viewing distance | Pixels per inch you need | Typical place |
|---|---|---|
| 1 ft (0.3 m) | 286 ppi | Held in your hands, a greeting card |
| 2 ft (0.6 m) | 143 ppi | A desk or a small frame on a shelf |
| 3 ft (0.9 m) | 96 ppi | A frame above a desk or a sofa |
| 5 ft (1.5 m) | 57 ppi | A poster across a small room |
| 6 ft (1.8 m) | 48 ppi | A big poster on a bedroom wall |
| 10 ft (3.0 m) | 29 ppi | A wall mural or a party banner |
| 15 ft (4.6 m) | 19 ppi | Stage backdrop, gym or hall |
Most posters are seen from 3 to 6 feet, so 50 to 100 pixels per inch is plenty. The poster maker shows the pixels per inch of your poster as soon as you load a picture.
How big can your picture go?
Divide the width of the picture in pixels by the pixels per inch you need. Here is what that means for common pictures:
| Picture | Pixels | Sharp up close (150 ppi) | Sharp from 4 ft (75 ppi) | Fine from 7 ft (40 ppi) |
|---|---|---|---|---|
| Social media picture | 1,080 × 1,350 | 7 in (18 cm) | 14 in (37 cm) | 27 in (69 cm) |
| Full HD screenshot | 1,920 × 1,080 | 13 in (33 cm) | 26 in (65 cm) | 48 in (122 cm) |
| 8 MP (older phone) | 3,264 × 2,448 | 22 in (55 cm) | 44 in (111 cm) | 82 in (207 cm) |
| 12 MP (most phones) | 4,032 × 3,024 | 27 in (68 cm) | 54 in (137 cm) | 101 in (256 cm) |
| 24 MP (camera) | 6,000 × 4,000 | 40 in (102 cm) | 80 in (203 cm) | 150 in (381 cm) |
| 48 MP (phone, full resolution mode) | 8,064 × 6,048 | 54 in (137 cm) | 108 in (273 cm) | 202 in (512 cm) |
A normal 12-megapixel phone photo makes a poster about 27 inches wide that is sharp even up close, and over 50 inches wide for a wall you see from across the room.
Where people lose resolution without noticing
- Pictures sent through chat apps are often compressed to 1,600 pixels or less. Ask for the original file, or use "send as document".
- Social media downloads are usually 1,080 pixels wide, enough for about 7 inches at full sharpness. Fine for a small print, soft as a big poster.
- Cropping throws away pixels. If you crop half the width of a photo, it can only be printed half as big at the same sharpness.
- Digital zoom on a phone does not add detail. Use the optical lenses or move closer.
What to do with a low-resolution picture
If the picture is small, you still have good options:
- Make a smaller poster, or plan to hang it where people see it from further away.
- Turn it into a halftone dot poster. A dot poster is made of large printed circles, so it looks crisp at any size, even from a small picture. It is the classic way to make a wall-sized print from almost anything.
- Upscale it with care. AI upscalers can add convincing detail to faces and landscapes, but they invent it, so check the result before printing a big poster.
DPI or PPI?
PPI (pixels per inch) describes the picture: how many of its pixels end up in each inch of paper. DPI (dots per inch) describes the printer: how many tiny ink dots it lays down. A home inkjet prints at 1,200 DPI or more no matter what, so the number that matters for sharpness is PPI.