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You photograph six pages of a form, convert them to a PDF, send it, and the reply says the document is unreadable. Or you print it and each page comes out as a postage stamp in the middle of a sheet of white.
The images were fine. What went wrong happened in the conversion, and it comes down to four settings that most converters either bury or decide for you.
A photo has no page size
This is the root of all four problems, and it is worth a moment.
A PDF page has physical dimensions. A4 is 210 by 297 millimetres; it means something when printed. A JPEG has no physical size at all — it is a grid of pixels, 4032 by 3024 of them, with no opinion about how large that should be on paper.
So when a converter turns a photo into a PDF page, it has to invent a physical size. There are two ways to do it:
- Make the page the photo. The PDF page becomes the photo's own proportions — a 4:3 page, which is not a paper size anyone owns.
- Put the photo on a page. Create an A4 or Letter page and place the image on it.
Many converters default to the first, because it is the obvious thing to do and it looks correct on screen. Then you print it, the printer tries to fit that strange 4:3 page onto A4, scales it down to fit the narrower dimension, and you get a small image floating in white.
Nothing was broken. The file just never had a page size anybody's printer wanted.
Fit or fill: the choice that crops your document
Once you are putting the photo on a real page, the proportions will not match — A4 is roughly 1:1.41, a phone photo is usually 4:3 or 3:4. Something has to give, and you get two options:
Fit scales the image until the whole of it is on the page. The mismatch becomes white bands at the top and bottom, or the sides. Nothing is lost.
Fill scales until the image covers the page completely, and whatever overflows is cropped off.
For a holiday photo, fill looks better. For a document, fill is dangerous, because the parts it crops are the edges — which is where page numbers, reference numbers, signature lines and form footers live. It crops the part you are least likely to check and most likely to need.
Default to fit for anything with text. Accept the white bands.
A4 or Letter, and why it bites
A4 is 210 x 297 mm. US Letter is 216 x 279 mm. Letter is slightly wider and noticeably shorter.
They are similar enough that the wrong choice rarely produces an obvious error. It produces a small one: content shifted, margins uneven, and — because Letter is 18 mm shorter — the possibility that the bottom of an A4-laid-out page falls off the end.
Rule of thumb: A4 unless you are sending to the US or Canada. If a portal names a size, use the one it names.
Margins and the printer's dead zone
Almost no consumer printer prints to the edge of the paper. There is an unprintable border, usually a few millimetres, and anything in it is simply not printed.
If you convert with zero margin, the image runs to the page edge — and on paper, a strip of it vanishes. On screen it looked perfect, which is how it reaches the person who needs to read the bit that is now missing.
A margin of around 10 mm costs you almost nothing and takes the content out of the dead zone. Do not overdo it: large margins shrink the image, and a shrunken photo of a document is harder to read, which was the original problem.
Rotation is not what you think
Two different sideways problems, with different fixes.
The photo was shot sideways. Straightforward — rotate it before converting.
The photo carries an orientation tag. Modern cameras store a rotation flag in the metadata rather than rotating the pixels. Viewers that read the tag display it upright; converters that ignore it place the raw pixels on the page. This is why a photo that looks correct in your gallery can land sideways in the PDF.
Either way, fix it in the converter, before exporting. Rotating in a PDF reader afterwards often only changes your view — the saved file can still open sideways for the recipient, which is the one person it matters for.
A checklist before you send it
Thirty seconds, and it catches nearly everything:
- Open the finished PDF, not the preview in the converter.
- Check page one and the last page. Order problems and missing pages show up at the ends.
- Look at all four edges of a page with text. If anything is touching an edge, your margin is too small, or fill cropped it.
- Zoom to 100% on the smallest text. If you cannot read it, neither can they.
- Check the page count matches the number of images you selected.
A note on the app I build
Disclosed interest: Foldra is mine.
It exists for exactly the four decisions above, which is why they are settings rather than assumptions: A4, Letter, or fit the page to the image if that is genuinely what you want; orientation and margins; a quality slider when the file has to come in under a limit; and page reordering and per-page rotation before you convert, by long-pressing to drag. It takes JPG, PNG, WebP and HEIC, combines any number of images into one multi-page PDF, and runs offline — the images are not uploaded anywhere.
The checklist above applies whatever you use. If you only do one thing from this post, set the page size to A4 or Letter instead of letting the photo decide.
Frequently asked questions
Why does my photo print so small as a PDF?
Because the converter made the page the size of the photo rather than putting the photo on a page. A 4:3 phone photo becomes a 4:3 PDF page, and when a printer fits that odd page onto A4 it scales it down and surrounds it with white.
Should I use fit or fill when converting images to PDF?
Fit, for anything with text near the edges. Fit scales the whole image onto the page and leaves white bands where the proportions differ. Fill crops the overflow to fill the page edge to edge, which is fine for a photograph and quietly removes the margins of a document.
A4 or Letter — which should I choose?
A4 almost everywhere, Letter in the US and Canada. They are close enough that the wrong one usually prints with a small shift rather than failing, which is exactly why it goes unnoticed until the bottom line of a form is missing.
Why is one page of my PDF sideways?
Because the photo carried an orientation tag the converter ignored, or because it was genuinely shot sideways. Rotate the page in the converter before exporting rather than after — rotating in a reader often only changes the view, not the file.
How do I combine several photos into one PDF?
Any image-to-PDF tool will do it. The things worth checking are that you can reorder pages before converting, set one page size for all of them, and rotate individual pages — otherwise you get the right pages in the wrong order and orientation.