Mac storage basics · Caches, logs and temporary files
Why is my Lightroom Classic catalog folder so big?
Short answer: Mostly the Previews.lrdata file. Discard 1:1 previews from Library → Previews, set them to auto-discard in Catalog Settings, and limit the Camera Raw cache.
Mostly previews. Lightroom Classic keeps a Previews.lrdata file next to the catalog, and full-size (1:1) and Smart Previews can grow very large.
- Library → Previews → Discard 1:1 Previews for folders you're not editing.
- In Catalog Settings → File Handling, set 1:1 previews to be discarded automatically after a period.
- Lower the Camera Raw cache size in Lightroom's Performance settings.
The previews are rebuilt when needed; your photos and edits aren't affected.