How do you reduce PDF file size on a Mac?

Person working on a Mac
Document shredder: cut the file size of a PDF

PDF remains a vastly popular document format, but it has one BIG problem: bloat. If your PDF document is stuffed with lots of photos, graphics or graphs the file size can balloon, which can make it tricky to send files by email, for example. So, how do you reduce PDF file size on a Mac?

It’s very simple to do, but not the least bit obvious. Let’s show you how it’s done.

Time needed: 2 minutes

Use Preview to reduce PDF file size on a Mac

  1. Open the PDF in Preview

    By default, if you open a PDF on a Mac it will open in the Preview app. If you’ve changed the default PDF handler to another app, right-click on the PDF file, choose Open With and select Preview from the drop-down list.

  2. Export the PDF

    The option to reduce the size of the PDF is tucked away in the Export menu. To find this, click File then Export in the Menu Bar at the top of the screen.

  3. Use the Quartz Filter menu

    Once you’ve selected Export, a window will appear on screen. The option to reduce the size of the PDF is hidden in the Quartz Filter menu, shown below. Select Reduce File Size from that drop-down. You might want to rename the PDF in Export As and before you hit Save.

The reduce file size of PDF option in Preview

What does reducing the file size do to the PDF?

It’s possible to dramatically cut the file size of your PDFs using the technique above. We reduced an 108-page report stuffed with graphics and charts, which was originally 5.1MB (already quite slim!) down to 2.6MB – almost chopping the file size in half.

However, that space saving does come at a cost and that’s image quality. Images are the easiest way to make savings, as text doesn’t take up much storage space. Hence, if you look at the before and after PDFs, you’ll probably notice a reduction in the image quality.

In our tests, it didn’t make the image quality unacceptably poor, but it’s definitely noticeable. Something to bear in mind if you’re working on a sales brochure or other publication where the image quality is key.

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About the author

Barry Collins

Barry has scribbled about tech for almost 20 years for The Sunday Times, PC Pro, WebUser, Which? and many others. He was once Deputy Editor of Mail Online and remains in therapy to this day. Email Barry at

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