How to reduce a Keynote file size
One menu command handles most of it. Keynote's Reduce File Size scales photos down to the size they are shown at and re-encodes video. Here is what it changes, what it will not fix, and what to do with the deck that is still too big to email afterwards.
File → Reduce File Size, explained
In Keynote for Mac, choose File → Reduce File Size. Apple's dialog lets you scale down large images to the resolution they are displayed at, remove the trimmed parts of movies and audio, and convert movies to a more compact format. Keynote shows the estimated saving before you commit; you can save the result as a copy so the original stays untouched.
For a typical client deck this is the difference between 600 MB and 150 MB. It does nothing to slides that are already lean, so if the number barely moves, the weight is somewhere the command does not reach.
What makes decks huge
Three things account for almost every oversized Keynote we see.
- Video straight from a phone or camera: 4K, 60 fps, minutes long. A single clip can outweigh the rest of the deck.
- Uncompressed PNG screenshots and renders dropped onto slides at full size, then scaled down in the layout. Keynote keeps the full file.
- Trimmed clips. Trimming in Keynote hides the footage; it does not delete it until you reduce the file.
Manual clean-up that works
- Re-export long videos at 1080p before placing them. Nobody sees 4K on a slide.
- Delete slides you skipped in the last three presentations. Hidden slides still ship.
- Replace an animated GIF with a short movie; movies compress far better.
- Check the master slides: a 40 MB background image on the master is on every slide.
When 200 MB is still too big to email
Most mail servers stop at 20–25 MB. A deck with any real video will never fit, and the workarounds (WeTransfer, a Dropbox folder, a compressed PDF) each lose something: the link expires, the recipient needs Keynote, or the video is gone.
The other route is to stop sending the file. Export the deck to HTML (File → Export To → HTML…), zip the folder, and upload it. The person you send it to opens a link; the video streams from a CDN instead of sitting in their inbox.
Sending a large deck as a link instead
Linkdeck accepts exports up to 200 MB on the free plan and 500 MB on Pro. On upload it compresses images and GIFs again and serves everything from a CDN, so the viewer only downloads what the current slide needs. Animations, builds, audio and hyperlinks play as Keynote exported them, on any phone or laptop, with no Apple Account.
Questions
What does Reduce File Size actually do?
Per Apple's guide, it can scale large images down to the resolution they are shown at, remove the trimmed portions of movies and audio, and convert movies to a smaller format. It does not touch text, shapes or animations.
How big can a Linkdeck upload be?
200 MB on the free plan, 500 MB on Pro. Images are compressed further on upload, so the hosted deck is usually smaller than the ZIP you sent.
Will the quality drop?
Images are downscaled to the size they are displayed at, which is invisible on most slides. Check any full-bleed photo and any slide you zoom into with a build; if it matters, keep the original copy.
Still too big? Upload the export; the viewer streams it
Export to HTML, zip, drop it here. Free for the first deck, up to 200 MB.