How to compress a PDF for email

Why email rejects big PDFs

Most email services cap attachments at around 20–25 MB, and many company mail servers set lower limits. Attachments also grow by roughly a third when they are sent, so a 20 MB PDF can already be too large. Scanned documents and PDFs full of photos are the usual culprits, because every page is a large image.

This guide is about getting under an email limit quickly. If you need a precise target size for an upload form, see how to reduce PDF file size; if sharpness matters most, see compressing without losing quality.

Step by step

1. 1Open Compress PDF and add your PDF. It is processed in your browser and not uploaded.
2. 2Start with 150 DPI and Standard quality — that is usually readable on screen and much smaller than a scan.
3. 3Compress and compare the new size with the original, which is shown next to it.
4. 4If it is still too big, try 72 DPI, or remove pages you don't need with Delete PDF Pages.
5. 5Download the smaller PDF and attach it to your email.

Picking settings that stay readable

Resolution decides how sharp each page is. 150 DPI suits reading on a screen; 72 DPI is smaller but small print can blur; 300 DPI is best if the recipient will print the document. Quality controls how strongly each page image is compressed — Standard is fine for most letters and forms, while Maximum keeps photos and fine lines cleaner at the cost of size.

Open the compressed file and zoom in on the smallest text before you send it. If you can read it comfortably, the recipient can too.

If compressing isn't enough

Some documents are simply too long for one email, however you compress them — a scanned book or a hundred-page photo report, for example. In that case it is usually kinder to the recipient to send fewer pages: remove blank pages, duplicate scans and appendices they don't need, or split the document into parts with clear names such as "Report part 1 of 3".

Another option is to share a link from a cloud storage service you already use instead of attaching the file. That avoids attachment limits altogether, though the recipient then needs access to that service.

Things to know before you send

Compression rebuilds each page as an image, so text in the result can no longer be selected or searched. Keep the original if the recipient needs to copy text from it.

Text-only PDFs are already small and may not shrink much. If one huge document still won't fit, Split PDF lets you send it as two or three emails instead.

Frequently asked questions