How to Make a PDF Small Enough to Email

First, find out what is actually heavy

PDF size almost always comes down to one of three things. Scanned pages, where each page is a full-colour photograph of a sheet of paper. Embedded images, where photos or screenshots were placed at their original resolution. Or embedded fonts, which add a fixed overhead but rarely more than a few hundred kilobytes.

A text-only PDF of thirty pages is typically well under a megabyte. If yours is 40 MB, it is not the text. It is images, and probably scans.

The quickest win: send fewer pages

Before compressing anything, ask whether the recipient needs the whole document. Extracting the three relevant pages from a sixty-page report takes seconds, produces a small file, and is usually more useful to the person receiving it. Our split tool does this in the browser without touching the original.

For scanned documents, rebuild rather than compress

If the PDF is a stack of scanned pages, the practical route is to work on the images. Where you still have the scans, resize them to around 2000 pixels on the long edge, save them as JPG at a moderate quality, and assemble them back into a PDF. A 40 MB scan set frequently comes back at 2 to 4 MB and remains perfectly legible.

Where you do not have the scans, re-scanning at 200 to 300 dpi in greyscale — rather than 600 dpi in colour — is faster than fighting the file you have.

What we do not offer, and why we are telling you

We do not have a general PDF compressor that recompresses the images inside an existing document. Doing that properly means unpacking every image stream, re-encoding it and rewriting the page resources, which is a substantial piece of work we have not built. Rather than send you to a page that quietly does very little, it is more useful to say so and describe what does work.

Other things that genuinely help

Print to PDF. Opening the document and using your operating system's 'Save as PDF' printer flattens it and often reduces size noticeably, at the cost of any interactive elements and sometimes the selectable text.

Send a link instead. Most mail providers cap attachments in the region of 20 to 25 MB, and many organisations set a much lower limit on what they will accept. For anything large, a shared link avoids the problem entirely and gives you the ability to revoke access later.

Split into parts. Two emails with half a document each is inelegant but it works, and it beats a bounced message.

Check the real limit before you optimise

Attachment limits apply to the encoded message, which is larger than the raw file — mail attachments are typically encoded in a way that adds roughly a third to their size. A 24 MB file will often fail against a stated 25 MB limit for exactly this reason. Leave a generous margin rather than tuning to the last megabyte.