How to shrink a PDF's file size on iPhone
You don't need special software to shrink a PDF's file size on iPhone. FernPDF runs entirely in Safari on iOS: open the tool, drop your file, download the result. Compression re-encodes the document on your device. Image-heavy and scanned PDFs shrink the most, often 60–90%.
On iPhone, you tap the drop zone to open the native picker, then choose Files, iCloud Drive, or Photos. Once the smaller file is ready, it downloads to the Files app, inside Downloads, ready to reopen, AirDrop, or attach to an email straight from there.
Safari's file picker is a full-screen sheet rather than a floating window, and there's no separate downloads icon on the Home Screen, everything routes through the Files app, iOS's equivalent of Finder.
Files from iCloud Drive or the Files app open directly in Safari, and processing happens on the phone itself: no app to install, and nothing uses your data plan to upload.
Step by step
- 1Open the Compress PDF Online Free: Reduce PDF File Size tool in Safari on iOS. No install, no account.
- 2Add your PDF: tap the drop zone to open the native picker, then choose Files, iCloud Drive, or Photos.
- 3Pick a level: Less, Recommended, or Strong, and preview the estimated savings.
- 4Click “Compress PDF” and download the smaller file. It lands in the Files app, inside Downloads, ready to reopen, AirDrop, or attach to an email straight from there.
Common questions
Every FernPDF tool processes files in your browser: read how the privacy model works, or verify it yourself in your network tab.