How to compress files for email
Know the attachment limits, then shrink PDFs, photos and documents to fit.
Know your attachment limit
Each provider caps attachment size, and the cap counts the encoded size, which is a bit larger than the file on disk — so leave headroom:
- Gmail — about 25 MB per message.
- Outlook.com — around 20 MB.
- Corporate / Exchange servers — often lower (10 MB is common), set by your admin.
Go over, and the message bounces or the provider forces you onto a cloud link.
Compress the right thing
- PDFs — usually the biggest culprit. Compress a PDF for email re-encodes its images to slip under the limit while keeping text sharp.
- Photos — camera images are huge. Compress image cuts them dramatically; for several photos, compress each rather than zipping (JPGs barely zip).
- Word / PowerPoint — size usually hides in embedded images; re-compressing those shrinks the file without touching your content.
Aim for well under the cap
Because encoding adds overhead and you may attach more than one file, target comfortably below the limit — for Gmail, keeping the total to a dozen megabytes or so is safe. Our tools let you set an exact size if your server is strict.
When it still won't fit
Don't crush a file into uselessness. Instead: split a large PDF into parts, send photos in two emails, or upload to cloud storage and paste a share link. These keep quality intact and sidestep the limit entirely.
Frequently asked questions
Does zipping files make them email-friendly?
Only for already-uncompressed data. JPGs, PNGs, PDFs and Office files are already compressed, so zipping them saves almost nothing — compress the contents instead.
What size should I target for Gmail?
Stay comfortably under 25 MB total. If you're attaching several files, compress each so the combined size has headroom.