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How to make a PDF small enough to email (without uploading it anywhere)

Why PDFs get too big for email, and five ways to shrink them: compression, splitting, lower-resolution scans, re-exporting and sharing links. Step by step.

PDF2 min readUpdated

Key takeaways

  • Most email services cap attachments at about 20–25 MB; many upload portals allow only 2–10 MB.
  • Scanned and photo-heavy PDFs shrink the most, often by 60–90%.
  • Text-only PDFs are usually already small. If one is huge, the cause is embedded images or fonts.
  • You can compress privately in your browser, without uploading confidential documents.
On this page
  1. Why is my PDF so big?
  2. Email size limits to aim for
  3. Method 1: Compress the PDF
  4. Method 2: Split it into parts
  5. Method 3: Scan at a sensible resolution
  6. Method 4: Re-export from the original
  7. Method 5: Send a link instead
  8. A privacy note

Why is my PDF so big?

A PDF's size comes almost entirely from what is inside it. Text costs very little: a 100-page report of plain text may be under 1 MB. The heavy items are images. A phone scan saves each page as a high-resolution photo, often 2–4 MB per page, so a 20-page scanned contract can reach 50 MB. Embedded fonts, high-resolution logos repeated on every page, and documents saved repeatedly with "incremental updates" also add weight.

Email size limits to aim for

Gmail lets you attach up to 25 MB; Outlook.com allows 20 MB. Larger files are automatically turned into a cloud link. In practice, aim for under 10 MB: the recipient's server may have a lower limit, and attachments grow by about a third when encoded for email. Government and university upload portals are often stricter, at 2–5 MB.

Method 1: Compress the PDF

For scans and image-heavy files, redrawing pages at a lower resolution is the most effective step. With Compress PDF, choose "Recommended" (110 dpi) first; it stays readable on screen. Use "Strong" for strict portals, and tick grayscale for black-and-white scans to save more. The trade-off is that text in the result becomes part of the image, so keep your original if you need to search or copy text.

Method 2: Split it into parts

If only some pages are needed, or a portal accepts several files, use Split PDF to extract the relevant pages or break the document into chunks. This keeps full quality and selectable text.

Method 3: Scan at a sensible resolution

For documents, 150–200 dpi in grayscale is plenty; 600 dpi colour is for archiving photographs. Most scanner apps have a "document" or "black and white" mode that produces files a fraction of the size.

Method 4: Re-export from the original

If the PDF came from Word, PowerPoint or Google Docs, export it again. In Word, choose File › Save As › PDF › Minimum size (publishing online). Images in the source document are the usual culprit, so compress large photos before inserting them with Compress images.

For very large files, upload them to a cloud drive you already trust and share a link with appropriate permissions. This avoids size limits entirely, but the file then lives on that service, so it suits documents you are comfortable storing there.

A privacy note

Many online compressors upload your PDF to their servers. For contracts, IDs, medical or financial records, use a tool that processes files locally. Toolkeel's PDF tools run in your browser, so the document never leaves your device.

Sources

  1. Google: Gmail attachment size limitssupport.google.com
Written by the Toolkeel team at Sole Digital Media

Fact-checked against the sources above. We test every tool we mention. Editorial policy.

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