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How to Compress a PDF on Mac — Free, No Adobe, No Preview Tricks

Compressing a PDF on Mac can be done for free in three ways: using Mac Preview's Quartz Filter (built-in but unpredictable — sometimes makes files larger), using a browser-based tool in Safari or Chrome (no install, choose compression level, consistent results), or using a desktop app like PDF Squeezer. For most Mac users, the browser method gives the best balance of control and quality. PDFWix runs in any Mac browser, processes the file on your device via WebAssembly, and never uploads your PDF to a server.

How to Compress a PDF on Mac — Free, No Adobe, No Preview Tricks

Compress a PDF on Mac free in Safari or Chrome — no Adobe, no Preview Quartz filter. Choose your compression level. No install, no signup, no watermark.

Tip: skip Preview's Quartz filter

Preview's built-in 'Reduce File Size' Quartz filter is famously aggressive — it downsamples every image to 150dpi regardless of content, which destroys scanned documents and photo-heavy PDFs. PDFWix Compress preserves image quality intelligently: the Recommended preset keeps photo PDFs visually identical, the Strong preset reduces aggressively only on inflated metadata and embedded thumbnails. For receipts and ID scans where legibility matters, always pick PDFWix over Preview's Quartz filter.

How it works

  1. Open Compress PDF — Open Safari or Chrome on your Mac and go to pdfwix.com/compress-pdf. No account needed.
  2. Upload your PDF — Drag the PDF from Finder onto the upload area or click Select file.
  3. Choose compression level — Pick Low, Recommended, or High depending on the trade-off between size and quality.
  4. Compress — Click Compress. Your browser processes the file locally with WebAssembly.
  5. Download — Click Download. The compressed PDF saves to your Mac's Downloads folder.

Frequently asked questions

Does Mac Preview compress PDFs well?

Preview's Reduce File Size filter works for basic use but has no quality control — it applies the same aggressive compression to every PDF regardless of content. For text-heavy PDFs it is adequate. For image-heavy or professional PDFs it often degrades quality noticeably or, in some cases, produces a file larger than…

Why does Mac Preview make my PDF bigger after compressing?

Preview's Quartz filter re-encodes all images at a fixed DPI. If the original PDF already contains compressed images at a lower DPI than Preview's target, the filter expands them and the output file is larger. This is a known limitation of the Quartz Filter approach. A browser-based compressor handles this case…

What is Quartz Filter Reduce File Size on Mac?

Quartz Filter is a macOS image processing pipeline built into Preview and other Mac apps. The Reduce File Size filter is a preset that resamples all images to a fixed resolution and applies JPEG compression. It has no quality control slider and cannot be customised without creating a custom Quartz filter in ColorSync…