How to Reduce PDF File Size for Email (Under the 25 MB Limit)
· 5 min read · Tips
Most email providers cap attachments at around 25 MB (Gmail and Outlook both do). Scanned documents and image-heavy PDFs blow past that easily. The good news: most of that weight is in the images, and you can usually cut a PDF by 70–90% without a noticeable drop in readability.
Why PDFs get so large
- Scanned pages stored as full-resolution photos (often 300 DPI or higher).
- Embedded images that were never downsized for screen use.
- Duplicate fonts and uncompressed data streams.
Shrink it in three steps
- Open the Compress PDF tool and add your file.
- Drag the quality slider — the live preview shows exactly how the page will look at that setting.
- Download the smaller file and check the before/after size shown on the page.
Choosing a quality level
Start at the recommended (middle) setting — it typically gets image-heavy scans well under the email limit while keeping text crisp. If you need it even smaller, slide toward 'smaller file' and watch the preview; if quality matters more than size, slide the other way. Because text in most PDFs stays sharp regardless, the slider mainly trades image detail for size.
Already compressed a file and it barely shrank? It is probably already optimised. Re-compressing an already-small PDF will not magically make it smaller — the tool never re-bloats a file.
Still too big?
If a single PDF is enormous because it contains dozens of pages, consider splitting it and sending the relevant pages only, or sharing a link instead of an attachment.
Split a PDF into smaller files
Frequently asked questions
Will compressing reduce text quality? No — text and vector graphics stay sharp. Compression mainly recompresses images.
Is my file uploaded? Compression runs on our server, in memory only — your PDF is never written to disk and is deleted the instant your download is ready.