How to Reduce PDF File Size for Email (Under 10 MB)

You have finished your report, saved it as a PDF, and then discovered it is 45 MB — far too large to attach to an email. This is one of the most common frustrations with PDF documents. Fortunately, reducing a PDF's file size is quick and free. Here is everything you need to know.

Why are PDFs so large?

PDF file size is almost always driven by images. A text-only PDF (like a typed contract) is typically under 200 KB no matter how many pages it has. The moment you add photographs, scanned pages, or exported presentation slides, the file size jumps dramatically. Each full-page scan at 300 DPI might be 2–4 MB, so a 20-page scanned document can easily exceed 50 MB.

Other factors that increase PDF file size include embedded fonts (though these are usually small), embedded video or audio files, and high-resolution product photos in brochures and catalogues.

Email attachment limits by provider

Before compressing, it helps to know your target size:

Gmail: 25 MB per attachment
Outlook / Hotmail: 20 MB per attachment
Yahoo Mail: 25 MB per attachment
Corporate email servers: Often 10 MB or even 5 MB

If you are emailing a business contact, aim for under 10 MB to be safe — you do not know what limit their corporate server enforces.

How to compress a PDF for email using PDF Ninjas

Go to the Compress PDF tool.
Upload your PDF.
Choose a compression level: Balanced works for most documents. Use Max Compression if you need the absolute smallest file size and can accept slightly reduced image quality.
Enter your email address and click Process.
Download the compressed PDF. The download screen shows you the before and after file sizes so you can confirm the reduction.

What to expect from compression

A scanned document or image-heavy PDF typically shrinks by 50–80% with Balanced compression. A 40 MB scanned contract becomes 8–15 MB. A 20 MB photo brochure becomes 4–8 MB. Text-only PDFs compress much less (10–30%) because there is no image data to reduce.

When compression is not enough

If your PDF is still too large after Max Compression, consider these alternatives:

Use a cloud link instead: Upload the file to Google Drive or OneDrive and share a link rather than an attachment. There is no size limit on shared links.
Split the PDF: If the document can be divided logically (e.g. by section), split it into smaller parts and send them in separate emails.
Reduce the source quality: If you are generating the PDF from a presentation or design tool, export it at a lower DPI setting (96 or 150 DPI is fine for screen reading; 300 DPI is only needed for print).

Does compression affect print quality?

For everyday email attachments that will be read on screen, Balanced compression looks completely fine. If the recipient plans to print the document at a large format (A3 or larger), use High Quality compression instead — it produces a slightly larger file but preserves sharper image detail for printing.