Nine times out of ten the file is fine and your printer is fine. They were built for two different paper standards that do not share a shape.
The world runs on two systems. Most of it uses ISO A-sizes, where A4 is 21.0 x 29.7 cm. The United States and Canada use Letter, which is 21.6 x 27.9 cm. Those are close enough to look interchangeable in a listing and far enough apart to ruin a print.
Letter is 0.6 cm wider and 1.8 cm shorter than A4. That is the whole problem.
The two paper worlds, in numbers you can check
Here are the sizes as defined in the CSS Paged Media specification and documented in MDN’s page-size reference, which states the ISO figures in millimetres and the North American ones in inches.
The ISO A-series, given directly in metric:
| Size | Dimensions |
|---|---|
| A5 | 14.8 x 21.0 cm |
| A4 | 21.0 x 29.7 cm |
| A3 | 29.7 x 42.0 cm |
The North American sizes are defined in inches, so these are converted at exactly 2.54 cm to the inch:
| Size | Source figure | Dimensions |
|---|---|---|
| Letter | 8.5 x 11 in | 21.6 x 27.9 cm |
| Legal | 8.5 x 14 in | 21.6 x 35.6 cm |
| Ledger / Tabloid | 11 x 17 in | 27.9 x 43.2 cm |
Notice something about the A-series that is not true of the other column. A5 doubled is A4. A4 doubled is A3. Every A size is exactly half the next, which means an A-series file scales between them perfectly and never needs cropping.
The North American sizes have no such relationship. Letter to Ledger is not a clean doubling of shape, so a file built for one does not drop neatly into the other.
The shape difference, and why 0.6 cm matters
What actually decides whether a print fits is not size. It is proportion.
A4 is 29.7 divided by 21.0, a ratio of about 1.414 to 1. Letter is 27.9 divided by 21.6, about 1.294 to 1. Letter is the squatter of the two.
A printer cannot change the shape of a picture. It can only scale it until one dimension fits, and then either cut off the overflow or leave the shortfall blank. Those are the two things you are seeing.
What happens when the wrong file meets the wrong paper
Take an A4 file, 21.0 x 29.7 cm, and print it on Letter, 21.6 x 27.9 cm. There are exactly two outcomes, depending on which setting your print dialog is using.
Fill the page. The printer scales the file until its width matches Letter’s 21.6 cm, which means scaling everything up by a factor of 1.028. The height goes up too, from 29.7 cm to about 30.5 cm. The paper is only 27.9 cm tall. Roughly 2.6 cm of your image has nowhere to go, so it gets cut, about 1.3 cm off the top and 1.3 cm off the bottom if the print is centred.
Fit the page. The printer scales the file down until its height fits Letter’s 27.9 cm, a factor of about 0.94. Now the width shrinks from 21.0 cm to about 19.8 cm, on a sheet 21.6 cm wide. You get roughly 1.8 cm of blank paper, about 0.9 cm down each side.
Print a Letter file on A4 and you get the mirror image of the same problem.
Neither outcome is a fault. Both are the printer doing the only two things it can do with a shape that does not match the paper.
How to tell which file you actually have
Open the file and check its dimensions before you print anything.
If it says 21.0 x 29.7 cm, or 210 x 297 mm, you have an A4 file and it wants A4 paper.
If it says 21.6 x 27.9 cm, or 8.5 x 11 inches, you have a Letter file and it wants Letter paper.
If it says something else entirely, you probably have a ratio file rather than a paper file, and that is a slightly different situation covered below.
If the shop only sold you one of them
This happens constantly, and it is fixable without reprinting anything at the wrong size.
The reliable move is to print at the file’s own proportions on the paper you have, accept the border, and trim. Choose the fit-to-page setting rather than fill-the-page, print the A4 file onto Letter, and you will get that 0.9 cm margin down each side. Trim it off with a craft knife and a metal ruler and you have an image at true A4 proportions, just slightly smaller than a full A4 sheet.
That is a far better outcome than the fill setting, which silently removes part of the artwork. If a print has a border, an edge, or a signature near the margin, filling will eat it.
The other option is to ask. Most sellers of digital prints have both files sitting in a folder and will send the other one. It costs them nothing.
If you are the one selling the files
The fix is to stop making the buyer solve it.
Include both. An A4 file and a Letter file, clearly labelled, in the same download. They are the same artwork exported twice, and shipping only one guarantees that a share of your buyers get a print that looks wrong through no fault of their own.
Label them by paper name, not by market. “A4” and “US Letter” are unambiguous. “International” and “Standard” are not, and the buyer who guesses wrong leaves the review.
If you also sell at frame sizes rather than paper sizes, keep those separate and say so. A file cut to fill a 30.5 x 40.6 cm frame is a different shape again, and a buyer who prints it at home on A4 will hit exactly the problem described above.
The same problem at poster size
Scaling up does not make this go away. It makes it bigger, because the gap scales too.
A3 is 29.7 x 42.0 cm. Ledger, the nearest North American size, is 27.9 x 43.2 cm. A3 is 1.8 cm wider and 1.2 cm shorter. Print an A3 file to fill a Ledger sheet and the crop is proportionally similar to the A4 case, but now you are losing centimetres of a piece meant to be looked at from across a room.
At poster size the trimming approach gets more appealing rather than less, because a 1 cm white margin on a large print reads as a deliberate mount rather than a mistake.
The quick version
Two paper systems, similar sizes, different shapes. A4 is taller and narrower, Letter is shorter and wider, and the 1.8 cm height difference is what crops your print or borders it.
Check the file’s dimensions before printing. Use fit-to-page rather than fill-the-page when the file and the paper disagree, so you lose margin instead of artwork. Trim the border if it bothers you.
And if you sell printables, include both files. It is one extra export and it removes the single most common reason a good print arrives looking wrong.
For everything else about getting a downloaded file onto a wall, our complete guide to sizing, printing, framing and hanging covers frame choice, paper weight and hanging heights.
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