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Print resolution against viewing distance
Normal 20/20 vision resolves detail of one arcminute, which works out to about 143 pixels per inch at 24 in and about 95 at 36 in; at 100 pixels per inch the pixels stop being resolvable beyond about 34 in. Northlight Images suggests viewing large prints from one to one and a half times the diagonal.
One pixel seen under one arcminute at the viewing distance. Angle exaggerated; schematic.
Pixels per inch the eye can resolve, by distance
Wikipedia gives 20/20 vision as the ability to resolve two points one arcminute apart, equal to 60 pixels per degree. At distance d inches one pixel per arcminute is 1 / (d x tan(1 arcminute)), about 3,438 / d pixels per inch. That formula is our arithmetic from the one-arcminute figure; no fetched page prints it.
| Viewing distance | Pixels per inch at one pixel per arcminute | Against ArtzFolio's 100 ppi print files |
|---|---|---|
| 12 in (30.5 cm) | 286 | 100 ppi is below it |
| 24 in (61 cm) | 143 | 100 ppi is below it |
| 36 in (91.4 cm) | 95 | 100 ppi is enough |
| 48 in (121.9 cm) | 72 | 100 ppi is enough |
| 60 in (152.4 cm) | 57 | 100 ppi is enough |
| 96 in (243.8 cm) | 36 | 100 ppi is enough |
| 120 in (304.8 cm) | 29 | 100 ppi is enough |
Viewing distance by print size
Viewing distance of one to one and a half times the diagonal is Northlight's rule of thumb. The pixels per inch column applies the arithmetic above at both distances, for sizes picked across the listed framed canvas range.
| Listed size | Diagonal | Distance at 1 to 1.5 x diagonal | Pixels per inch needed |
|---|---|---|---|
| 6 x 4 in | 7.2 in | 7.2 to 10.8 in | 477 to 318 |
| 10 x 8 in | 12.8 in | 12.8 to 19.2 in | 268 to 179 |
| 20 x 16 in | 25.6 in | 25.6 to 38.4 in | 134 to 89 |
| 36 x 18 in | 40.2 in | 40.2 to 60.4 in | 85 to 57 |
| 60 x 48 in | 76.8 in | 76.8 to 115.3 in | 45 to 30 |
What the other sources say
| Source | Figure | Scope |
|---|---|---|
| Wikipedia: Pixel density | The unaided eye generally cannot separate detail beyond 300 ppi, depending on distance and acuity | Screens held close |
| Wikipedia: Retina display | 300 ppi at 10 to 12 in, equal to 52 to 63 pixels per degree; a critic argued 477 ppi at 12 in | Phones |
| Apple (iPhone 4) | 326 ppi so dense the eye cannot distinguish pixels at normal distance | Phones |
| Northlight Images | 286 ppi at 24 in and 57 ppi at 120 in, for very high contrast and optimal light; halve for average conditions | Prints |
| Photo Review Australia | Above 250 dpi rated excellent, 180 to 250 good, 180 and below poor with detail loss noticeable; people stand farther from larger pictures | Prints |
Our 3,438 / d table uses one pixel per arcminute, while Northlight's table counts a line pair, so its numbers are about twice as high, and Photo Review's printing rule is stricter at close range. Twenty-twenty (one arcminute) is a benchmark: Wikipedia also gives about 0.47 arcminute, roughly 128 pixels per degree, as the eye's limit, so sharp eyes need more than the table shows. These are rules of thumb and the sources do not fully agree. For a large piece on a wall, the question to ask is how far away you will stand; see the pixels guide for what each listed size needs.
Sources
- Wikipedia: Visual acuity (fetched 2026-11-12)
- Wikipedia: Pixel density (fetched 2026-11-12)
- Wikipedia: Retina display (fetched 2026-11-12)
- Apple Newsroom: Apple presents iPhone 4 (company statement) (fetched 2026-11-12)
- Northlight Images: print resolution versus viewing distance (fetched 2026-11-12)
- Photo Review Australia: how large should you print (fetched 2026-11-12)
Figures from these pages are paraphrased; each page was fetched and read on 2026-11-12. Where two sources differ, both are shown. The arcminute formula is our arithmetic from Wikipedia's one-arcminute figure.
Related pages
- Pixels needed for each print size
- Effective pixels per inch table
- PPI versus DPI
- Largest print size for your photo
- Image interpolation