How to Reduce PDF File Size for Email Attachments

You've written the email, attached the PDF, hit Send — and get an error. "Attachment too large." Gmail caps attachments at 25MB, Outlook at 20MB, and many corporate email systems set even lower limits. When your PDF is too big, you need to shrink it fast.

Option 1: Compress the PDF (Best for Most Cases)

PDFably's Compress PDF tool optimizes the internal structure of your PDF to reduce file size without affecting visible quality. This works especially well on documents that haven't been previously optimized.

1. Open the Compress PDF tool
2. Upload your oversized PDF
3. Click Compress — the tool shows you the before and after file sizes
4. Download the smaller version

Typical results range from 15-60% size reduction depending on the document. Text-heavy PDFs with unoptimized internal structures see the biggest improvements.

Option 2: Split Into Smaller Parts

If compression alone doesn't bring your PDF under the email limit, or if the document is significantly oversized, consider splitting it into parts using PDFably's Split tool. Send Part 1 in one email and Part 2 in a follow-up.

For example, a 45MB report can be split into pages 1-50 and pages 51-100, each small enough to email separately. The recipient can then merge them back together if needed.

Option 3: Remove Unnecessary Pages

Does the recipient really need every page? Often, large PDFs contain appendices, reference sections, or supplementary material that isn't relevant to everyone. Use PDFably's Remove Pages tool to strip out what isn't needed before sending.

This approach serves double duty — it reduces file size and makes the document more focused and easier for the recipient to read.

Why PDFs Get So Large

Embedded images: The primary culprit. A single high-resolution photo can add several megabytes. Documents with charts, diagrams, letterheads, or scanned pages accumulate image data quickly.

Redundant data: PDF editors sometimes leave behind orphaned objects, duplicate fonts, or revision history. PDFably's compression cleans up this structural waste.

Scanned pages: Each scanned page is essentially a full-page photograph. A 10-page scanned document can easily reach 30-40MB because every page is a high-resolution image.

Email Size Limits by Provider

Gmail allows 25MB attachments. Outlook.com allows 20MB. Yahoo Mail allows 25MB. Most corporate Exchange servers cap at 10-20MB. If you're sending to someone at a company, assume 10MB as a safe limit unless you know otherwise.

Alternative: Share Large Files Differently

If your PDF is still too large after compression and page removal, consider uploading it to a cloud service (Google Drive, Dropbox, OneDrive) and sharing a link instead of an attachment. But if the document is sensitive, add password protection before uploading to any cloud service.