How to Compress a PDF for Email — Free, In-Browser
Quick answer: Drop your PDF into Compress PDF, pick "screen" quality, then download. Most 25 MB PDFs come out under the 20 MB Gmail / 20 MB Outlook attachment cap in a single pass.
Email providers cap attachments at around 20–25 MB, and scanned documents or image-heavy PDFs blow past that limit easily. The good news is that most of that weight is recoverable: PDFs usually contain images saved at far higher resolution than email needs, so re-compressing them shrinks the file dramatically without making the text any harder to read.
Steps
- Open the free Compress PDF tool.
- Drop your file in. Pick "screen" or "ebook" quality — both keep text crisp.
- Click Compress, wait a few seconds, then download. Attach the smaller file to your email.
Why PDFs get so large
The single biggest cause of an oversized PDF is images. A document scanned at 600 DPI, or one built from phone photos, stores far more pixels than any screen will ever display. Compression works by resampling those images down to a sensible resolution and re-encoding them — which is why a 30 MB scan can drop below 5 MB with no visible loss on screen.
Which quality setting to choose
For email, "screen" quality is almost always the right choice — it targets on-screen reading and gives the smallest file. Use "ebook" if you want a little more headroom for zooming in. Reserve higher-quality settings for documents you intend to print, where the extra resolution actually shows.
If a single pass doesn't get you under the limit, your PDF may simply have too many pages of imagery — in that case, splitting it into two emails is usually easier than over-compressing into mush.
Everything runs in your browser — your PDF never leaves your device.