How to Clear the Lightroom Classic Camera Raw Cache and 1:1 Previews

Lightroom Classic quietly accumulates two distinct caches that can consume tens of gigabytes on your Mac: the Camera Raw cache, which accelerates raw file processing, and the Previews.lrdata bundle, which stores rendered preview images for every photo in your catalog. Many photographers discover these files only after a low-disk-space warning. This guide explains what each one is, how to clear the Lightroom Camera Raw cache safely, and how to delete or trim your 1:1 previews without harming your originals.

Understanding the Two Caches

Lightroom Classic maintains separate caches for separate purposes. Conflating them leads to confusion — and sometimes deleting the wrong thing.

Your original RAW and JPEG files are never stored inside either cache. Deleting these folders does not touch your photos.

How to Purge the Camera Raw Cache in Lightroom

Adobe provides a built-in control to cap and purge the Camera Raw cache. This is the safest and recommended first step.

1. Open Lightroom Classic and go to Lightroom Classic > Preferences (or press Cmd ,).
2. Click the Performance tab.
3. Under Camera Raw Cache Settings, note the Maximum Size slider. Lower it to 1–5 GB if you want to reduce how much Lightroom keeps going forward.
4. Click Purge Cache to immediately delete everything currently cached.
5. Click OK to close Preferences.

After purging, Lightroom will re-cache files as you open them. You may notice slightly slower initial load times for raw files you have not opened recently — this is normal and temporary.

Clearing the Camera Raw Cache Manually via Finder

If Lightroom is not installed or you want to reclaim space while Lightroom is closed, you can delete the cache folder directly.

1. Quit Lightroom Classic completely.
2. In Finder, press Cmd Shift G and enter:

~/Library/Caches/Adobe/CameraRaw/Cache

3. Select all contents inside the Cache folder (not the folder itself) and move them to Trash.
4. Empty Trash.

Do not delete the CameraRaw parent folder or any Settings subfolders — those store your camera profiles and lens corrections, not cache data.

How to Delete Lightroom 1:1 Previews (Previews.lrdata)

The Previews.lrdata bundle is almost always larger than the Camera Raw cache, and it is the more impactful target when you need to reclaim disk space. Lightroom stores standard and 1:1 (full-resolution) previews here so it can display images quickly without re-reading every original file.

Option 1: Discard 1:1 Previews from Inside Lightroom

This is the most targeted approach. It removes only the large full-resolution previews while keeping the smaller standard previews intact.

1. In the Library module, select all photos in a folder or collection (press Cmd A).
2. Go to Library > Previews > Discard 1:1 Previews.
3. Confirm the dialog. Lightroom removes the 1:1 data and shrinks Previews.lrdata.

You can also automate this: in Catalog Settings > File Handling, set Automatically Discard 1:1 Previews to After 30 Days. Lightroom will prune them on its own without any manual intervention.

Option 2: Delete Previews.lrdata Entirely

When you want the maximum space reclaim in one step, delete the whole bundle. Lightroom will regenerate standard previews the next time you browse your catalog — you will see a brief "loading" spinner on thumbnails.

1. Quit Lightroom Classic.
2. Locate your catalog. The default location is:

~/Pictures/Lightroom/

3. You will see files named something like Lightroom Catalog.lrcat and a bundle named Lightroom Catalog Previews.lrdata. The .lrdata bundle is a macOS package (a folder that looks like a file).
4. Move Lightroom Catalog Previews.lrdata to Trash.
5. Empty Trash, then reopen Lightroom.

If you use a non-default catalog location, open Lightroom's Catalog Settings > General tab to see the exact path before closing Lightroom.

What About Smart Previews.lrdata?

Smart Previews are DNG-based lossy copies that allow editing when your originals are on an external drive that is not connected. Deleting Smart Previews.lrdata is safe as long as you have access to your original files. If you rely on smart previews for a mobile workflow or offline editing, keep them.

Finding Oversized Preview Bundles with a Disk Scanner

If you have multiple Lightroom catalogs — one per year is common — the combined Previews.lrdata files across all of them can be surprisingly large. Tracking them all down manually is tedious.

Crumb's Visualize tab scans your entire Mac and surfaces the largest files and folders by size, making it straightforward to spot .lrdata bundles that have grown unchecked in old catalog locations. When Crumb flags one of these bundles, you can verify in Finder whether the corresponding catalog is still active before deciding to delete. Because preview deletion is permanent (until Lightroom regenerates them), it is worth confirming you are not removing previews for a catalog you still use regularly.

To download Crumb and run a scan, no account is required — install the package and click Clean or Visualize from the menu bar.

After Cleaning: What to Expect

• Thumbnails will reload. After deleting Previews.lrdata, the gray "loading" spinner appears on thumbnails the first time you browse each folder. This is cosmetic; your photos are intact.
• 1:1 zoom will be slow initially. Lightroom renders the 1:1 preview on demand the first time you zoom in. It caches the result again immediately, so subsequent views are fast.
• Raw file processing may feel slightly slower. If you purged the Camera Raw cache, expect a brief slowdown the first time you develop each image. The cache fills back up automatically.
• No edits are lost. Develop settings, metadata, and keywords live in the .lrcat catalog file, not in any cache. Clearing caches never touches your edit history.

A Recurring Maintenance Habit

The most practical long-term approach combines two things: set Lightroom to automatically discard 1:1 previews after 30 days (Catalog Settings), and cap the Camera Raw cache to a size that fits your workflow — 5 GB is plenty for most photographers. With both settings in place, preview bloat becomes self-correcting and you rarely need to intervene manually.

For photographers who keep archives going back many years across multiple catalogs, a periodic disk scan is useful to catch preview bundles that slipped out of sight when a catalog was moved or renamed. That is where a visualizer pays for itself in time saved hunting through folder trees.