How to make a PDF small enough to email

October 8, 2026 · All guides

How large an attachment can be

Every email service has a limit. Gmail's is 25 MB per message. Microsoft's Outlook allows 20 MB for most personal accounts, and work accounts on Exchange often start at 10 MB, set by the company's administrator. The limit counts the whole message, and attachments grow by about a third on the way, so a file well under the limit is the safe aim.

Why PDFs get large

Text costs almost nothing: a hundred pages of it fit in a few hundred kilobytes. Size comes from pictures. A phone photo, a page scanned in colour at high resolution, or a screenshot pasted at full size can each add several megabytes, and a scanned document is nothing but pictures.

Fonts are the other cost. A PDF often carries every font it uses, sometimes whole, and the same picture can be stored more than once.

Compress it

  1. Open Compress PDF and choose the file. Its current size is shown.
  2. Choose a level. Light keeps pictures at full size and only tidies the file. Balanced shrinks large pictures. Smallest is made for email and the web.
  3. Compress. You see how much smaller it got before you save it. If a level would not make the file smaller, it is left exactly as it was.

At every level, text and drawings are left untouched, so they stay perfectly sharp; only pictures are scaled and recompressed. Fonts are trimmed to the letters the document uses, and repeated pictures and unused objects are dropped.

If it is still too large

  • Send fewer pages. Delete the pages the reader does not need, such as blank pages from a scan or appendices.
  • Send it in parts. Split the PDF into ranges and attach each to its own message.
  • Rescan smaller. A document scanned in black and white or greyscale, at 150 to 200 dots per inch, is a fraction of the size of a colour scan at 600, and reads just as well.
  • Photos of documents: take them at a normal size rather than the camera's largest, then make the PDF and compress it.
  • Share a link instead. Every large mail service can put a file in cloud storage and send a link to it.

Keep the original

Compressing pictures throws detail away for good. Save the compressed copy as a new file and keep the original, in case someone needs to print it or zoom in.

Tools in this guide