How to Compress a PDF on iPhone
· 5 min read · ConvertEase Team
Quick answer
To compress a PDF on iPhone, install the free ConvertEase app, tap Compress, choose your PDF, pick a compression level, and tap Compress. A smaller PDF is created on your iPhone in seconds — ready to email or upload, with no file uploaded to any server.
"The attachment is too large." It's one of the most annoying errors on a phone, and it usually shows up right when you're trying to send a scanned contract, a portfolio, or a form. The fix is to compress the PDF so it fits the size limit — and you can do it on your iPhone in under a minute.
Why PDFs get so big (and how compression helps)
A PDF's size is almost always driven by the images inside it — especially scanned pages and high-resolution photos. A 10-page scanned document can easily be 30–50 MB, well past the ~25 MB limit most email services allow. Compression re-encodes those images at a sensible resolution, which can cut the file size by 50–90% while keeping the pages clearly readable.
How to compress a PDF on iPhone (step by step)
- Download ConvertEase free from the App Store and open it.
- Tap Compress and choose the PDF you want to shrink.
- Pick a compression level — higher compression = smaller file.
- Tap Compress, then save or share the smaller PDF straight from your iPhone.
You can also shrink photos and videos the same way — see the iPhone file compressor for PDF, image and video compression.
Which compression level should I choose?
| Goal | Recommended level | Result |
|---|---|---|
| Email a scanned document | Medium / "Email" | Big size cut, fully readable text |
| Upload to a portal with a strict cap | High | Smallest file, slightly softer images |
| Archive but keep it crisp | Low | Modest size cut, near-original quality |
Tip: compress before you sign or send
If you scanned a multi-page document with the Camera or Notes app, it's worth compressing it before attaching. You'll avoid the "file too large" bounce-back entirely, and the recipient downloads it faster too.
Frequently asked questions
Use the free ConvertEase app: tap Compress, choose your PDF, pick a compression level, tap Compress. A smaller PDF is created on your iPhone in seconds — no computer or website needed.
Most email providers cap attachments around 20–25 MB. PDFs with scanned pages or high-resolution images easily exceed that. Compressing reduces the embedded images so the file fits.
Compression mainly shrinks the images inside the PDF. A balanced level keeps text crisp and pages readable while cutting size dramatically. ConvertEase lets you choose the level.
Yes — ConvertEase compresses 100% on your iPhone, so the PDF is never uploaded. Safer than online compressors that require an upload of sensitive documents.