Hanging guide
What resolution do I need to print art at a given size?
About 150 dpi on paper and 100 dpi on canvas, for art viewed from a metre or two. That means an A2 paper print (59.4 cm) needs a file around 3,500 pixels on its long edge, and an A1 (84.1 cm) needs about 4,960. The familiar 300 dpi standard is for things held in the hand, and applying it to wall art rules out prints that would look perfectly sharp.
Standard print sizes
| Size | Centimetres | Inches | Pixels for 150 dpi |
|---|---|---|---|
| A4 | 29.7 × 21 | 11.7 × 8.3 | 1,755 |
| A3 | 42 × 29.7 | 16.5 × 11.7 | 2,480 |
| A2 | 59.4 × 42 | 23.4 × 16.5 | 3,510 |
| A1 | 84.1 × 59.4 | 33.1 × 23.4 | 4,965 |
| 50 × 70 cm | 70 × 50 | 27.6 × 19.7 | 4,134 |
| 70 × 100 cm | 100 × 70 | 39.4 × 27.6 | 5,906 |
Pixels are for the long edge. For canvas at 100 dpi, multiply by two thirds.
Why 300 dpi is the wrong number for a wall
300 dpi comes from print for the hand: books, magazines, photographs held at 30-40 cm. The eye resolves roughly one minute of arc, so the detail it can pick out depends entirely on how far away it is. Double the distance and you halve the resolution required.
Wall art is looked at from one to two metres. 150 dpi is genuinely sharp at that distance, and it is the floor most print-on-demand services will accept for large formats. Insisting on 300 dpi for a 84 cm print means demanding a 9,900 pixel file, which rules out a great deal of work that would have printed beautifully.
Canvas is different, and not as a compromise
Canvas weave is around 0.3 mm. A 100 dpi dot is 0.25 mm. The texture is therefore coarser than the dots, and it - not the file - sets the limit on visible detail. This is why gallery-wrap canvas is routinely produced at 100-150 dpi and looks right.
The practical consequence is useful: a file that will only make an A2 on paper will often make a 90 cm canvas, which is frequently the size the wall actually wanted.
How this shows up in Murello
We apply exactly these floors. A size is only offered if the source can produce it - 150 dpi on paper, 100 on canvas - and each size shows the resolution it would print at. If a piece cannot honestly make an A1, we do not offer an A1, because the render shows the size the button sells.
Questions people also ask
Is 150 dpi really enough for a large print?
For something on a wall, yes. Resolution requirements scale with viewing distance, and nobody examines a 84 cm print from 30 cm away. 300 dpi is the standard for a book page held at reading distance; at one to two metres the eye cannot resolve the difference.
Why can canvas go lower than paper?
The weave gets there first. Canvas texture is around 0.3 mm, coarser than a 100 dpi dot at 0.25 mm, so the substrate limits visible detail before the file does. Putting a higher-resolution file on canvas does not produce a sharper print.
How many pixels do I need for an A2 print?
About 3,500 on the long edge for 150 dpi. A2 is 59.4 cm, which is 23.4 inches, and 23.4 × 150 = 3,510.
What are A3, A2 and A1 in centimetres?
A3 is 42 × 29.7 cm, A2 is 59.4 × 42 cm, A1 is 84.1 × 59.4 cm. Each size is the previous one doubled, so A2 is two A3s and A1 is two A2s.
Can I enlarge a small file to print bigger?
Enlarging adds pixels but not detail, and on a large print the softness shows. It is better to choose a size the file genuinely supports than to print beyond it and be disappointed by something that looked fine on screen.
Do museum images have enough resolution to print?
It varies more than you would expect. Many open-access scans are 3,000-4,000 pixels, which is comfortable at A3 and A2 and short of A1 on paper. Some are far larger. It is worth checking the pixel dimensions before choosing a size.