You don't need an app for this
Bundling several photos or scans into a single PDF — for an application, an expense report, a form — is a task every operating system already handles. No shady online converter that uploads your documents, no paid app. Here's the built-in way on each platform, plus how to keep the resulting PDF from ballooning.
Windows 11
Windows has a built-in "Microsoft Print to PDF" printer:
- Select all images in File Explorer, right-click → Print.
- Choose Microsoft Print to PDF as the printer.
- Pick the layout (usually "Full page photo"), then Print → choose a filename.
All selected images land in one PDF, in the order they were selected.
macOS
- Select the images in Finder and open them in Preview.
- In the sidebar, arrange them in the order you want (drag to reorder).
- File → Print → PDF → Save as PDF.
Preview also lets you merge existing PDFs and drag pages between them.
iPhone
- From Photos: select the images → Share → Print → pinch-zoom out on the preview to turn it into a PDF → Share → Save to Files.
- From the Files app: select images → the "..." menu → "Create PDF".
- For documents: the Notes app can scan pages and export them directly as a PDF (Notes → camera → Scan Documents).
Android
- Google Drive: the plus button → Scan turns camera captures into a multi-page PDF.
- Print to PDF: open the images, Share → Print → select "Save as PDF" as the printer.
- Exact menus vary by manufacturer, but a "Save as PDF" print option is almost always available.
The big trap: huge PDFs
A PDF is mostly just a container — its size depends on how the images inside are compressed. A PDF made from raw, full-resolution photos or 600-dpi scans can be enormous. The fix is order of operations: optimize the images first, then bundle them.
- Resize each image to a sensible size (~1600 px for on-screen documents) with the resize tool.
- Compress as JPG at quality 75–80 (compression).
- Then combine the optimized images into the PDF.
Done this way, a stack of scans that would be 40 MB raw ends up at a couple of MB — small enough for any upload limit, and still perfectly readable.
In short
Every OS can make a PDF from images with built-in tools — Print to PDF on Windows/Android, Preview on Mac, Print/Files on iPhone. Just optimize the images before bundling, or the PDF gets needlessly large.