How to combine photos into one PDF

Photographing documents with a phone has largely replaced using a scanner, and it works well until you need to send the result. Twelve separate images in an email is awkward for everyone; one PDF is a document.

The conversion itself is simple. The decisions around it are what determine whether the result looks deliberate or thrown together.

Getting the order right first

Images are almost always sorted by filename, and phone cameras produce names like IMG_20260114_093312.jpg — which sort correctly by luck, because the timestamp is in the name.

Where it goes wrong is renamed files. page1, page2 … page10 sorts as page1, page10, page11, page2 — because alphabetical comparison looks at characters and 1 comes before 2. This is the single most common cause of a scrambled photo PDF.

Two fixes, and the first is permanent:

• Zero-pad the numbers: page01, page02, page10. Then alphabetical and numerical order agree, everywhere, forever.
• Reorder before converting, if the tool lets you drag them.

Check the order before you convert, not after. Rebuilding a PDF because page 10 landed second is entirely avoidable.

Page size: the decision that shows

This is where photo PDFs usually look wrong, and it has one cause.

A phone photo is typically 4:3 or 3:4. An A4 page is roughly 1:1.41 — noticeably taller and narrower. Put a 3:4 photo on an A4 page and you get thick white bands top and bottom.

Two approaches:

Match the page to the image. Each page is exactly the shape of its photo. No borders, nothing wasted, and the PDF looks like a set of photographs — which is what it is. This is right for anything that will be read on screen.

Use a standard paper size. Every page is A4 or Letter and the image is fitted inside. There will be white space, but the document prints predictably and files alongside other documents. This is right for anything going to a printer or into a records system.

The mistake is choosing a paper size out of habit for something nobody will print.

Fit or fill

If you do use a standard page, there is a second choice.

Fit puts the whole image on the page, with borders where the shapes disagree. Nothing is lost.

Fill scales the image until it covers the page and crops whatever hangs over the edges. It looks tidier and it cuts content off — which is fine for a decorative photo and disastrous for a document, where the cropped part is usually the margin containing a reference number.

For anything with text on it, fit. Always.

Making the photos worth reading

The conversion cannot rescue a poor photograph, and a few habits at capture time do more than any setting afterwards:

• Flat surface, even light. The biggest single improvement. A page held in one hand curves, and the curve shows.
• Camera parallel to the page. Shooting at an angle produces a trapezoid that no page size will square up.
• Watch your own shadow. Standing between the window and the page is the classic mistake.
• Fill the frame. Cropping later throws away pixels you could have used.

A dedicated scanning app is genuinely better than the plain camera for this: they detect the page edges and correct the perspective, which the camera app does not.

File size

Photo PDFs get large fast. A modern phone photo is 3–6 MB, so twelve of them make a 40–70 MB PDF — past most email limits.

The fix is compression, not splitting. Compress PDF re-encodes the images at a lower quality; for photographs of documents the drop in quality is usually invisible while the size falls dramatically. A 50 MB scan bundle routinely comes back under 5 MB and still perfectly readable.

Compress after combining, not before. One pass over the finished document beats twelve passes over the parts.

When the images are already in a folder or a zip

If someone has sent you an archive, you do not need to unpack it. ZIP to PDF converts everything inside and merges the results in order — and it sorts numerically, so page2 comes before page10 rather than after it.

Making the text searchable

A PDF of photographs contains no text, only pictures. You cannot search it or copy from it.

If you need that — and for anything going into an archive you probably do — run OCR afterwards. PDF to Text reads the pixels and gives you the words. It recovers the writing, not the layout, which is worth knowing before you expect a formatted document back.

Orientation, when the photos are mixed

A set of photos where some are portrait and some are landscape is the awkward case, and there is no setting that makes it perfect.

Two honest choices:

Pick one orientation and fit everything into it. The landscape shots get white bands above and below, the portrait ones fill the page. Consistent, slightly wasteful, and the right answer when the document will be printed.

Let each page match its image. Nothing is wasted and every photo is as large as possible. The document is uneven to flip through on screen and awkward to print.

For receipts, forms and anything going to somebody official, take the first. For a personal album, the second.

Getting scanned documents to look scanned

Photographs of paper have a particular problem: they look like photographs of paper. Grey, slightly uneven, with a shadow along one edge.

Running each image through Enhance before combining fixes most of that — the black-and-white option in particular turns a grey phone photo of a receipt into something that reads as a scan.

It also makes the PDF dramatically smaller, because a pure black-and-white image compresses far better than a photograph of the same page.

File size, and one number worth knowing

Modern phone photos are 3-5 MB each. Twelve of them is 50 MB before you have added anything.

If the finished PDF has to be emailed, that is over every limit there is. Compress PDF afterwards will usually take it under 10 MB with no visible difference on a receipt or a form, because photographs are exactly what compression handles well.