How to compress a PDF for email attachments
The short version: open Compress PDF, upload the file, pick Balanced, and check the size. For most scanned or image-heavy PDFs that's enough to clear a 25 MB (Gmail) or 20 MB (Outlook) limit.
Compress PDF
Reduce PDF file size by rendering pages as compressed images.
Know the limit you're up against
- Gmail: 25 MB per message (all attachments combined). Above that it switches to a Drive link.
- Outlook.com: 20 MB. Corporate Exchange: often 10 MB.
- The recipient's server also has a limit. If you don't know it, aim for under 10 MB to be safe.
The steps
- Open Compress PDF and upload the PDF.
- Choose Balanced and download; check the reported size against your target.
- If it's still too large, try Smallest, or use the options below.
Why some PDFs shrink and others don't
Compress PDF converts each page to a compressed image. Scanned documents, photos and screenshot-heavy pages have lots of image data to squeeze, so they shrink a lot. A digitally exported text document is already small and mostly text — there's little to remove, so expect only a modest reduction.
Note the trade-off: the output's text is no longer selectable, because pages become images. For a scan you're emailing, that's usually irrelevant.
If compression isn't enough
- Split it. Send the PDF in two emails using Split PDF, or only attach the part the recipient needs.
- Compress the images before building the PDF. If you assembled it from photos, shrink them with Compress Image first.
- Send a link. Upload to a cloud drive and paste a share link — no size limit, and the recipient always gets the latest version.
- Combining several PDFs to send? Merge PDF first, then compress the single file once.
Do it now
Open Compress PDF and get under the limit.
Frequently asked questions
- What's the attachment limit for common email providers?
- Gmail: 25 MB. Outlook.com: 20 MB. Many corporate mail servers are stricter, often 10 MB. The receiving server's limit matters too, so aim well under.
- Does Gmail really let me send larger files?
- Over 25 MB, Gmail automatically uploads the file to Google Drive and sends a link instead of a true attachment. That works, but the recipient needs Drive access and the file isn't in the message itself.
- Will compressing make my PDF unreadable?
- For scans and photo-heavy PDFs, no — Balanced quality stays readable. Genuine digital text is re-rendered as an image and can look slightly soft when zoomed in at the Smallest setting.
- My PDF barely shrank. Why?
- It's already a lean text PDF with no large images to re-compress. If it's still too big, split it or send a Drive/link share instead.
Related guides
- How to compress a PDF without wrecking it
What actually makes PDFs large, why some compressors do more damage than others, and how to pick the right approach for your file.
- How to compress a PDF to under 1 MB
A 1 MB upload limit is common on application portals. Here's what's realistic, how to get there, and when 1 MB simply isn't possible without losing the text.
- How to convert images to PDF (JPG, PNG, phone photos)
Turn one or several JPG or PNG images into a single PDF, in the right page order — what the tool does, the steps, and the common snags.
Compress PDF
Reduce PDF file size by rendering pages as compressed images.