How to Compress a PDF on Mac (Free, Better Than Preview)
macOS Preview can export a smaller PDF using its "Reduce File Size" Quartz filter, but it's a blunt instrument — it often over-compresses images into mush or barely shrinks the file at all, with no control in between. A dedicated compressor gives you actual control over the size-versus-quality trade-off, free and in the browser.
Steps: Compress PDF on Mac
- 1
Open Compress PDF
In any browser on your Mac (Safari, Chrome, Arc), open the Compress PDF tool. Nothing to install.
- 2
Upload and pick a level
Add your PDF and choose a compression level — Medium is the balanced default; use High when you need the smallest possible file for an email limit.
- 3
Download and check
Download the compressed file and check the before/after size. If it's still too large, re-run at a higher level.
Why this beats Preview's built-in option
Preview's Quartz filter applies one fixed, aggressive setting — you either accept whatever it does or you don't. It's notorious for either destroying image quality or making almost no difference, depending on the file, with nothing you can adjust.
A proper compressor works by recompressing the embedded images (which is what actually bloats most PDFs) at a level you choose, so your text stays sharp while the file shrinks — and it tells you the before/after size so you know what you got.
What actually makes your PDF large
In almost every oversized PDF, the culprit is embedded images — scans, screenshots, or photos — not the text. That's why compression can shrink the file substantially while keeping text perfectly crisp: it's working on the images, not the words.
Frequently asked questions
Why not just use Preview's Reduce File Size?
Preview applies one fixed Quartz filter with no control, so it often over-compresses images or barely shrinks the file. A dedicated compressor lets you pick the level and shows you the before/after size.
Will compressing blur my text?
No — compression recompresses embedded images, not text, so text stays sharp at every level while the file gets smaller.
Is it free on Mac?
Yes, free in any browser with no watermark and no sign-up.
How small can it go?
It depends on how image-heavy the file is. Start at Medium, check the result, and re-run at High if you need it smaller.