Short version: open the free tool, drop your file, download the result. Nothing is uploaded.

Steps

In Safari, open WBS JPG to PDF.
Tap the box, then Photo Library, and pick one or more photos (or Choose File for pictures saved in Files).
Put them in order with the arrows if you picked several, and choose A4 or US Letter.
Tap Make PDF, then Download. The PDF goes to the Files app, in Downloads. Share it from there by email, Messages or AirDrop.

Method 1: Safari (several photos, your order, no upload)

The steps above build the PDF inside Safari, on the phone. The photos are not uploaded anywhere, which matters for an ID, a passport page or a signed form. iPhone photos are usually HEIC; when you pick them from the photo library, iOS normally hands them over as JPG, and Safari can read HEIC files directly anyway.

Method 2: the Files app

In Photos, select the pictures, tap Share and choose Save to Files.
Open the Files app and go to that folder.
Tap ⋯ (More) → Select, tap the images, then tap ⋯ at the bottom and choose Create PDF.

It's quick. The pages follow the order you tapped the files, and you can't rearrange them afterwards.

Method 3: the Print trick

In Photos, select the picture(s), tap Share → Print.
Spread two fingers on the preview (zoom in). It opens as a PDF.
Tap Share again and choose Save to Files.

This works on any iOS version but adds the print margins of the default paper size.

Which should I use?

For one photo, any of them. For a multi-page document photographed page by page, Method 1 is the easiest to get in the right order. If you need a combined PDF that also includes an existing PDF, make the photo PDF first, then join them with how to combine PDFs on iPhone.

More free guides

All tools: WBS Tools · All apps: Wood Between Studio apps