How to Reduce PDF File Size on Mac (The Actual Method)
The short answer
Reduce a PDF’s file size on a Mac with Preview’s Reduce File Size filter (File → Export → Quartz Filter), an online compressor, or the print-to-PDF trick at lower quality. Preview is built in and free; online tools give you more control. What doesn’t work: deleting pages, which barely changes size.
Preview’s Reduce File Size (built-in)
- Open the PDF in Preview.
- File → Export…
- Set the Quartz Filter to Reduce File Size.
- Save as a new file. Check the result before deleting the original.
This re-compresses the images inside the PDF. For a text-heavy document it often cuts the size by half with no visible change; for photo-heavy PDFs, expect the images to soften.
When Preview isn’t enough
Preview’s filter is one-size-fits-all — no quality slider. If the result is still too big (or looks bad), an online compressor (see PDF tools) lets you choose the compression level and usually squeezes harder. Upload, pick a level, download, compare.
The honest part about making PDFs smaller
Here’s the truth people learn the hard way:
- Images are 95% of a PDF’s weight. Text and vectors weigh almost nothing. If your PDF is heavy, it’s the photos — so compression success depends on them, not on the page count. Deleting pages rarely helps; removing pages and compressing are different jobs.
- “Reduce file size” can look bad. On image-heavy documents, Preview’s aggressive filter smudges. If the text gets fuzzy when zoomed, dial it back — an online tool with levels beats Preview’s single setting here.
- The real fix is at the source. If you make PDFs with photos regularly, resize the images before exporting (see how to make a PDF). Compression after the fact is the emergency brake, not the driving style.