How to Compress a PDF on Mac (Built-In, No Apps)
The short answer
Compress a PDF on a Mac three ways, all free: Preview’s export with a smaller filter, an online compressor, or re-printing at lower quality. Preview is the built-in one and handles most files; online tools win for big documents. The goal is the same — a smaller file that still looks right.
Compress with Preview (built-in, no upload)
- Open the PDF in Preview.
- File → Export.
- Click the Quartz Filter dropdown → Reduce File Size.
- Save as a new file, and check the result.
This re-encodes the PDF at lower image quality. For text-heavy documents it usually halves the size with no visible change; for image-heavy files, expect some softening. Keep the original until you’ve checked the output.
Compress with an online tool
Preview’s filter is basic — one setting, no control. For precise control (compression level, target size, what gets downgraded), an online compressor (see the PDF tools page) gives you options and typically squeezes harder. Upload, pick the level, download. Works when Preview’s result isn’t small enough.
The honest part
Three things to know about compressing on a Mac:
- Preview’s filter can’t fix everything. If the PDF is one giant photo, Reduce File Size makes it fuzzy fast. For real image-heavy documents, use the online route and check the quality setting.
- “Compressed” isn’t always smaller. PDFs built from pure text or vector graphics are already tight — compression may barely change them. That’s not a bug, that’s a text PDF being efficient.
- Why it’s big matters. If the file is heavy because of embedded photos, the real fix is at the source — resize the images before making the PDF, as covered in how to make a PDF. Compression after the fact is the band-aid.
Quick reality check after compressing: open the result and zoom into the text. If it’s still crisp at 200%, you’re fine. If it’s smudged, back off the compression level.