Compressing
How to Compress a PDF on Mac (Free, No Install)
Shrink a large PDF on a Mac for free. Set exact levels or hit a size target in your browser — no extra software beyond Preview and Safari.
Hamza M.
PDF Workflow Editor
A PDF that refuses to fit an email or an upload form is a familiar Mac problem. Preview can save a smaller version, but its controls are blunt and its savings uneven. A browser-based compressor gives you precise control over how much a file shrinks.
Here is how to compress a PDF on a Mac for free, with Preview and with a browser tool.
Compress with Preview (built in)
- 1Open the PDF in Preview on your Mac.
- 2Choose File > Export.
- 3Open the Quartz Filter menu and pick Reduce File Size.
- 4Click Save and check the new file size.
Preview’s Reduce File Size is a preset with a fixed lever — it helps, but you cannot choose how aggressively it compresses, and the result can go soft on image-heavy pages. For a quick tidy it is fine; for a specific size target it is unpredictable.
Compress with a browser tool (precise levels)
- 1In Safari or Chrome on your Mac, open the Compress PDF tool.
- 2Drag the PDF from Finder into the tool, or click to browse and select it.
- 3Pick a compression level — light keeps images crisp, heavy makes the smallest file.
- 4Tap compress and check the result size.
- 5Download the smaller PDF back to your Mac.
Because the compression runs in the browser, a sensitive file stays on your Mac instead of being uploaded to a server.
Hitting a specific size limit
| Limit | What to do |
|---|---|
| Under 10 MB | Light compression handles most documents |
| Under 5 MB | Choose medium and re-check |
| Under 2 MB | Heavy compression, then verify readability |
| Under 1 MB | Remove images first, then compress at a heavy level |
Why is my PDF still too large?
- Full-page scans carry a huge image payload that resists modern compression
- Pictures placed at print resolution but displayed small waste megabytes
- Repeated editing layers accumulate invisible overhead
If heavy compression is still not enough, the fastest win is usually at the source: remove unneeded pages, delete oversized images, and re-scan documents at lower resolution in grayscale.
Do it now
Compress PDF
Reduce file size while maintaining quality. It runs in this browser tab — your file is not uploaded anywhere.
Open Compress PDFFrequently asked questions
How do I compress a PDF on Mac for free?+
Use Preview’s Export with the Reduce File Size filter for a quick result, or a browser-based compressor in Safari or Chrome for precise levels. Both are free and need no install.
Does Preview compress PDFs?+
Yes — File > Export > Quartz Filter > Reduce File Size gives a smaller file, but its single preset gives you no control over how much quality is traded away.
Which compression level should I use?+
Start with light for crisp images and text. If the file is still too large, step up to a heavier level and preview the result at 100% zoom before sending it.
Is my PDF uploaded to a server when I compress it?+
No. When you use a browser-based compressor, the file is processed on your Mac and never leaves your device.
Why did my PDF barely shrink?+
Either it was already optimised, or it is mostly text — text-only PDFs are already small and have little to remove. Large files are image-heavy, which is where compression pays off.