How to Reduce PDF File Size for Email

How big can an email attachment be?

Every email provider caps the total size of a message, and that cap covers the message text plus all attachments together. The common limits are:

There’s a catch most people don’t know about: attachments are encoded as text (Base64) when they travel through email, which makes them roughly 33% bigger in transit. A 20 MB PDF can arrive as about 27 MB, which is why a file that looks “just under the limit” still bounces. And even when your mail sends, the recipient’s server may have a lower limit than yours.

Why is my PDF so big?

Text on its own is tiny — a 50-page contract that was exported from Word is often well under 1 MB. When a PDF is tens of megabytes, the weight almost always comes from one of these:

• Scanned pages. A scanner or phone scanning app stores every page as a photo. At 300 DPI in color, each page can easily be 1–3 MB.
• High-resolution photos. Images dropped into a document at full camera resolution (12+ megapixels) are kept at that size even if they’re printed small.
• Embedded fonts. Each unusual font adds its own data. This matters for small files, but rarely explains a huge one.
• Repeated saves and edits. Some editors append changes rather than rewriting the file, so old content lingers.

Knowing which case you’re in tells you what will work. Image-heavy PDFs compress dramatically. A mostly-text PDF that’s already small won’t get much smaller, and that’s fine — it’s probably not the file causing the problem.

How to compress a PDF for email, step by step

The Compress PDF tool on FaaTools works in your browser, so the file is never uploaded — useful when the PDF is a contract, payslip or medical record.

1. Open Compress PDF and drop your file into the upload area (or tap to choose it on a phone).
2. Start with Balanced. It keeps text readable on screen and in print while cutting a meaningful amount of size.
3. Look at the before/after sizes shown on the page. If the result is under about 10 MB, download it and you’re done.
4. Still too big? Try Smallest size. It reduces image resolution further — fine for reading on screen, so check that small print is still legible.
5. Open the downloaded file, zoom in on the smallest text and skim every page before you send it.

When compression isn’t enough

If a document is very long or you need every page in high quality, you have a few other options that are often better than squeezing quality further:

• Send only the pages that matter. Use Split PDF to extract the pages the recipient actually needs, or Organize PDF to delete blank pages and duplicates.
• Split into parts. Break a large file into two or three PDFs and send them in separate emails, labelled “Part 1 of 3” and so on.
• Re-scan at a lower setting. For paperwork, 150–200 DPI grayscale is usually plenty and produces far smaller files than 300+ DPI color.
• Share a link. For anything over 25 MB, a cloud link (Google Drive, OneDrive, iCloud, Dropbox) is the practical answer. Check the sharing permissions before you send it.

A quick checklist before you hit send

• The attachment total is under 10 MB (or under your recipient’s known limit).
• You opened the compressed file and every page is readable, including signatures and small print.
• The file name tells the recipient what it is — “2026-Lease-Agreement-Signed.pdf” beats “scan0042.pdf”.
• If the PDF contains sensitive information, consider adding a password with Protect PDF and sharing the password by a different channel, such as a text message.