The short answer: a 24 megapixel file prints a 40 × 60 cm picture beautifully, with pixels left over, and most people asking the question already have more than they need. The interesting part is why, and where the real limit sits, because it is not the number printed on the camera box.
Pixels have no size until you pick one
A photo file has no size in centimetres. It is a grid of pixels, and it only becomes 10 × 15 cm or 80 × 120 cm when somebody decides how tightly to pack that grid onto paper. That packing is measured in dots per inch, or DPI, and it is the one number in this whole subject that matters.
The sum is one line long. Take the pixels along one edge and divide by the length of that edge in inches. A 6000 pixel edge printed 60 cm long is 6000 divided by 23.6, which comes to 254 DPI. Print the same file 90 cm long and those same pixels spread further apart: 169 DPI. Nothing was lost. The paper got bigger and the file stayed the same, which is what the drawing beside this is showing.
So there is no such thing as a file being big enough. There is only big enough for a particular size, and the real question is what happens when you go past it.
The number nobody mentions is how far away you stand
300 DPI is the figure everyone repeats. It comes from things you hold at reading distance: a magazine, a book, something 30 cm from your face. At that distance your eye can pick out roughly 300 separate things per inch and no more, so 300 DPI is the point where extra pixels stop buying you anything.
A picture on a wall is not held at reading distance. You look at a 40 × 60 cm print from a metre or more, and at a metre your eye can pick out about 150 DPI. At three metres it is closer to 75. This is not a compromise or a trick. It is why a billboard printed at fifteen dots to the inch looks perfectly sharp from a car, and why big prints are made from files that would embarrass a magazine.
Which gives you a handy rule. The bigger the print, the further away it gets looked at, and the fewer pixels per inch it needs. Print size and required sharpness pull in opposite directions, and that is the quiet reason big prints are far easier than the 300 DPI folklore makes them sound.
Where 200 DPI comes from
The catalogue lists, for every photograph, the sizes it prints at 200 DPI or better once it has been cropped to that shape. 200 is a deliberate choice. It is comfortably more than your eye can pick out at wall distance, so the print still holds up when somebody walks right up and puts their nose against the frame, which people do with a photograph they have just bought.
That list is where quality stays excellent. It is not a limit, and it is worth saying so plainly, because plenty of shops present it as one. You get the full file. Print it bigger whenever you like. The picture softens gradually as the dots spread out, it does not fail at any particular number, and canvas in particular is regularly printed well past the list, because the weave is coarser than the pixels and you look at it from across the room. The only hard limit on this site is the licence, which is a legal thing rather than anything to do with the file.
Cropping is where the pixels really go
You rarely lose sharpness to the print size. You lose it earlier, to cropping, and cropping costs more than it feels like it should, because you are cutting area, not length. Trim 10% off each edge and 19% of the file has gone. Trim 20% and you are down to 64% of the pixels you started with.
The shape of the frame does the same thing without anyone choosing it. A camera shoots 3:2. A 40 × 60 cm print is also 3:2, so that one costs nothing. A 50 × 70 cm print is not, and squeezing a 3:2 picture into it throws away about 7% of the long edge before any ink is laid down. Square prints are the worst: a third of the picture has to go.
That is why the print-size table on each photograph works out the crop rather than just dividing. It refuses any size that would cost more than 18% of the long edge, because a size you can only reach by butchering the composition is not really a size the picture prints at.
Which is why the files come in several shapes
Every photograph in the shop comes as more than one file: a square crop, a 3:2, and a wider one. Each is made from the full-size original rather than trimmed out of a smaller export afterwards. That matters for exactly the reason above. A square made properly from the original keeps far more pixels than a square you cut out of a 3:2 JPEG at home.
So when the table on a photograph says it prints well at a size, it has already looked at all the shapes you get and picked the one that suits. You do not have to do any sums. Choose the shape that matches your frame and print it.
The numbers, if you want them
Two columns, because there are two honest answers. 200 DPI is the fine-art standard, sharp from any distance, including right up close. 300 DPI is the point past which no eye can tell any difference at all, and it is only worth chasing for small prints you hold in your hand.
| Print size | At 200 DPI | At 300 DPI | Needed |
|---|---|---|---|
| 10 × 15 cm | 787 × 1181 | 1181 × 1772 | 0.9 MP |
| 20 × 30 cm | 1575 × 2362 | 2362 × 3543 | 3.7 MP |
| A4 · 21 × 30 cm | 1654 × 2339 | 2480 × 3508 | 3.9 MP |
| 30 × 40 cm | 2362 × 3150 | 3543 × 4724 | 7.4 MP |
| A3 · 30 × 42 cm | 2339 × 3307 | 3508 × 4961 | 7.8 MP |
| 40 × 60 cm | 3150 × 4724 | 4724 × 7087 | 14.9 MP |
| 50 × 70 cm | 3937 × 5512 | 5906 × 8268 | 21.7 MP |
| 60 × 90 cm | 4724 × 7087 | 7087 × 10630 | 33.5 MP |
| 80 × 120 cm | 6299 × 9449 | 9449 × 14173 | 59.5 MP |
Read the last column against the wall, not against the spec sheet. A 24 megapixel file clears 40 × 60 cm comfortably and prints 60 × 90 cm at 169 DPI, which on a wall is a photograph nobody would ever question. The table says where the arithmetic is flawless, not where the picture stops working.
So, the 40 × 60 cm print
14.9 megapixels at 200 DPI, uncropped. Any camera made in the last fifteen years clears that, most phones clear it, and every photograph in this shop clears it with room left over. If you are choosing a file to print at that size, the resolution is almost certainly not what will decide whether you like the result.
What will decide it: whether the picture was sharp when it was taken, whether it was exposed well enough that the shadows are not full of noise, and what it is printed on. A soft file at 400 DPI is a soft print. A crisp file at 180 DPI is a crisp print. No amount of resolution rescues a photograph that missed focus, and no reasonable shortage of it ruins one that did not.
When you genuinely are short
It happens, usually with an old file or a heavy crop. Three things to do, in order. Print it smaller, which costs nothing and is always the right first move. Print it on a surface that hides the shortfall: canvas, textured rag, anything with a tooth of its own. Or upscale it, which modern tools do well enough for a wall, though they invent detail rather than recovering it, so judge the result at the size you will hang it rather than at 100% on a screen.
What not to do is print small and hope. A picture short of pixels looks worse at 20 cm held in the hand than at 80 cm hung across a room, because the hand is where the eye can still count them.
The short version
- Pixels have no size. DPI is pixels divided by inches, and it is the only number.
- 300 DPI is for things held in the hand. Wall prints need far less.
- 200 DPI is the standard used here: excellent from any distance, and not a ceiling.
- A 40 × 60 cm print wants 14.9 MP uncropped, which almost everything has.
- Cropping costs area, not length. 20% off each edge spends over a third of the file.
- Sharpness at capture beats resolution every time.