I made this simple table for personal use, than I thought it may came in handy to others too, so here we are.
It sums up how many megapixels do you need to print on each of the more common paper sizes available.
Given that the level of quality requested varies according to the kind of image – a portrait will be more enlargeable without artifacts or softness than a detailed landscape, for example – I’ve set three thresholds at 200, 260 and 300 dpi.
Please note that here we are talking about PRINT resolution, not PRINTER one.
If you don’t have this point clear please read one of the basic introductions available online. Let’s suffice to say that normally you will have to “stretch” the megapixel of your picture onto the area you intend to print; to have a quality result you don’t want to stretch them too much, and that’s what I’m talking about.
Printer resolution, on the other end, refers to the way printers manage to actually create an image putting thousand of ink dots one after the other on a piece of paper.
While print resolution – how many megapixels you need to cover the area of a piece of paper – it is alway the same regardless of the device used to create the image on paper, printer resolution varies wildly between models, makers and technologies used.
And now let’s look at the table. In the first column you find the paper format; in the seconds its size; in the third, fourth and fifth how many megapixels do you need for each print resolution, from the worst (200 dpi, in red) to the best (300 dpi, in green). You may pull it off with 200 dpi if the viewing distance for your print is not very close, especially if there is an actual physical impediment for the people to getting closer; otherwise everyone usually tends to stuck its nose to the print searching for more detail – and at 200 dpi this detail it will simply not be there.
In the last column I’ve listed how many shots you will need to use if you decide to join multiple frames in a matrix fashion to achieve a resolution of 300dpi with a 21-24 Megapixels camera* (first number is the total of shots needed, then how many shots rows x columns).
*With a 20% margin of juxtaposition to join the frames flawlessly
| Paper format |
Paper size |
200dpi | 260dpi | 300dpi | N° of shots [rows x columns] |
| A0 | 1189 x 841mm 46.8 x 33.1″ |
62 | 89 | 140 | 15 [ 5 x 3 ] |
| 800 x 800mm 31.4 x 31.4″ |
39 | 57 | 89 | 9 [ 3 x 3 ] | |
| A1 | 841 x 594mm 33.1 x 23.4″ |
31 | 45 | 70 | 6 [ 3 x 2 ] |
| 700 x 700mm 27.5 x 27.5″ |
30 | 44 | 68 | 6 [ 3 x 2 ] | |
| 600 x 600mm 23.6 x 23.6″ |
22 | 32 | 50 | 4 [ 2 x 2 ] | |
| A2 | 594 x 420mm 23.4 x 16.5″ |
22 | 35 | 2 [ 2 x 1 ] | |
| 500 x 500mm 19.6 x 19.6″ |
22 | 35 | 2 [ 2 x 1 ] | ||
| A3 | 420 x 297mm 16.5 x 11.7″ |
11 | 17 | 1 |
