How to compress a PDF on iPhone

Compress PDFs on iPhone in Safari. Turn a 40 MB scan into a 4 MB attachment without losing readable quality.

You scanned a six-page contract with the iPhone's Notes app, tried to email it, and Gmail bounced it back: attachment too large. The phone made a 48 MB PDF for what should be a 3 MB document.

iOS has no built-in PDF compressor. Safari has Flint.

Why iPhone scans are so big

Apple's scanner saves each page as a high-resolution image embedded in the PDF. That's great for archival quality, terrible for email. A ten-page scan can easily top 60 MB. Nothing in iOS will reduce that — Files won't, Mail won't, Photos won't.

Flint's compressor downsamples those embedded images intelligently. Text stays sharp, photos stay readable, file size drops by 80–95% on most scans.

How to compress, step by step

Save the PDF to Files (long-press in Mail or Notes, Save to Files). Open Safari, go to flintpdf.com, tap the compressor. Upload the file. Pick a quality level — Medium is the right answer 90% of the time. Download the smaller PDF back to Files.

The whole thing takes about 30 seconds for a typical 10-page scan.

When compression isn't enough

Some PDFs are big because they have 200 pages of high-res images. Compression helps, but if you only need pages 1–10 to send, use split PDF or delete PDF pages to drop the rest first. A 10-page compressed extract beats a 200-page compressed monster every time.

FAQ

Will compression make my PDF look blurry?

Medium compression keeps text crisp and images perfectly readable on screen and in print. Heavy compression is more aggressive — fine for archival or quick email, less ideal for client deliverables. Try Medium first; only drop lower if the file is still too big.

Why doesn't iOS have a built-in compressor?

iOS optimises for fidelity — it assumes you'd rather have a perfect scan than a small file. That's a reasonable default for archival, but it's why email attachments fail constantly. A browser tool fills the gap without needing to change iOS settings.

Does compressing remove text searchability?

No. If the PDF has a text layer (from OCR or being born digital), Flint preserves it. The compression targets embedded images, not the searchable text. Image-only scans stay image-only, but searchable PDFs stay searchable.

Next time Gmail bounces an attachment, compress the PDF in Safari and try again. The 30 seconds you spend is the difference between sending it and rewriting the email.

Try it now

Drop a PDF in and you'll be done in seconds — no install, files private to your account.

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How to Compress a PDF on iPhone (Free) | Flint — Flint PDF