Most email providers reject attachments above roughly 20-25 MB. A PDF full of photos, scans or high-resolution graphics blows past that easily. Compressing it is the fix - here is how to do it well.
What actually makes a PDF big
It is almost always images. A page of text is tiny; a single full-page scan at 600 DPI can be several megabytes. Good compression works by re-sampling those images down to a sensible resolution and re-encoding them - the text and layout stay exactly where they are.
Compress it
- Open Compress PDF and drop your file in.
- Pick a level: Strong (smallest, ~72 DPI, great for screen-only reading), Recommended (~150 DPI, the best balance), or Light (~300 DPI, keeps print quality).
- Click Compress PDF and check the before/after size shown on the result.
We never return a file larger than the one you uploaded, so you can safely try a stronger level and compare.
Choosing the right level
- Emailing to read on screen? Strong or Recommended is ideal.
- They might print it? Use Light to preserve 300 DPI image quality.
- Still too big? The document may be better split - send the relevant pages only with Extract pages or Split PDF.
A note on privacy
Compression is one of the few jobs that genuinely needs a server (it uses Ghostscript). Your file is sent over an encrypted connection, compressed, handed back, and deleted on the spot - we never store or log it. Everyday tools like merging and rotating stay entirely in your browser.