Make a PowerPoint or Keynote PDF smaller on a Mac

Why presentation PDFs get so big

Most of the size is pictures. Photos dropped into slides are often several times larger than the slide can show, and the export keeps them that way. Screenshots saved as JPEG, repeated background images and slides copied from other decks add more. Text and shapes are tiny by comparison.

What you can try for free first

1. Reduce the pictures in PowerPoint. On a Mac, choose File > Reduce File Size, pick a picture quality and apply it to all pictures, then export again. Work on a copy: cropped areas are removed for good.
2. Choose a lower quality in Keynote. File > Export To > PDF, then set Image Quality to Good or Better instead of Best.
3. Use Preview as a last resort. Open the PDF in Preview, choose File > Export and pick the Reduce File Size filter. It is quick, but pictures can become very soft.

Shrink it with Slide PRESS Basic (free)

Slide PRESS lets PowerPoint or Keynote do the export, then decides how every picture is kept, so you choose the balance between size and sharpness.

1. Download Slide PRESS Basic for Mac from its page and open it.
2. Drop your deck (PowerPoint or Keynote) or an existing PDF on the window.
3. Choose PDF and one of four qualities: High Quality (lossless), Balanced, Screen or Smallest File. Balanced suits most emails and uploads.
4. Press Export. The queue shows the size before and after, and the result is never larger than the original.

It runs on your Mac with the Office or iWork app you already have. Nothing is uploaded and there is no account.

What the free edition does not do

BASIC exports to PDF, PNG and JPEG at four quality levels. Asking for an exact target size (for example "under 10 MB"), putting back the untouched original pictures, PDF passwords, whole folders and the command line are part of Slide PRESS ADVANCED.