How to compress a PDF on a Mac

macOS ships a PDF compressor inside Preview, and it works, with one catch: it downsamples every image hard and gives you no say in how much. Here is that route, and the browser route for when you need to choose.

The built-in way on a Mac: Preview

  1. 01

    Open the PDF in Preview and choose File → Export (not Export as PDF).

  2. 02

    In the export sheet, open the Quartz Filter menu and pick Reduce File Size.

  3. 03

    Give the copy a new name so the original stays untouched, then click Save.

  4. 04

    Check the result. If scans have turned to mush, the filter is the reason — there is no strength setting.

Where it falls short

  • One fixed setting. Images are resampled to a low resolution whether they need it or not, so photos and scans often come out visibly blurry.
  • Text-only PDFs barely shrink, because there is nothing for the filter to downsample.
  • Export writes a new file; Save does not apply the filter.

Do it in the browser instead

The same Compress PDF tool as the main page, running in Safari or Chrome on a Mac. Nothing is installed and the file is processed on your device.

Processed in your browser. This file never leaves your device.

  1. 01

    Choose the PDF

    Open the tool in Safari or Chrome on your Mac and choose the file, or drag it from the Finder straight onto the page.

  2. 02

    Pick a mode

    Rebuild keeps the text sharp and selectable; Flatten to images is for scans, with three quality levels to choose from.

  3. 03

    Download the result

    Click Compress PDF. The page reports the before and after size, and says plainly if the file did not get smaller.

Preview or the browser tool?

 PreviewPDF Spree
CostFree, built inFree, no account
Text stays selectableYesYes
File leaves your deviceNoNo — processed in the browser
Works on other devicesNo, this platform onlyYes, any modern browser

Compress PDF on a Mac: questions

The same task on other devices

More PDF tasks on a Mac

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