How to Clear the QuickLook Cache on macOS (When Previews Show Wrong Thumbnails)

If you press Space on a file in Finder and the preview looks nothing like the current version of that file, you are running into a stale QuickLook thumbnail. Knowing how to clear the QuickLook cache on Mac is one of those small maintenance tasks that pays off every time you rename a project folder, overwrite a design file, or update a PDF and then wonder why the old version keeps showing up. This guide covers every method — from a single Terminal command to a full cache wipe — and explains what is actually happening under the hood so you can decide how aggressive you need to be.

What Is the QuickLook Cache and Where Does It Live?

QuickLook is the system framework that generates previews when you press Space in Finder or hover over icons in column view. To avoid re-rendering the same file repeatedly, macOS stores generated thumbnails and previews in a dedicated cache folder. On modern macOS (Ventura, Sonoma, Sequoia, and the upcoming Tahoe release), that cache lives in a sandboxed per-user directory:

• ~/Library/Caches/com.apple.QuickLook.thumbnailcache

On older systems or shared machines you may also see a legacy location at /var/folders/ inside a UUID-named subdirectory, but the user-level path above is what matters for most people. The cache can quietly grow to several hundred megabytes on a machine that handles a lot of large images, Keynote decks, or video files.

Why Previews Go Stale

QuickLook uses a file's inode, modification date, and size as a cache key. When any of those values change, macOS is supposed to regenerate the thumbnail automatically. In practice this does not always happen cleanly:

• Files edited by third-party apps that write to a temp file and then rename it — changing the inode without updating the expected metadata.
• Files restored from a Time Machine or cloud backup where the modification date is preserved but the content differs.
• Rapid overwrites during a build pipeline or design export, where the OS has not had time to invalidate the old entry.
• Corrupted cache entries after a hard shutdown or storage hiccup.

In each case the fix is the same: force QuickLook to discard the stale entry and regenerate it from the current file on disk.

How to Clear the QuickLook Cache on Mac: Step-by-Step

The fastest and most reliable method is a single Terminal command. It quits the running QuickLook server, which causes macOS to delete its in-memory state and invalidate the on-disk cache automatically.

1. Open Terminal (Applications > Utilities > Terminal, or search in Spotlight).
2. Run the following command:
   qlmanage -r cache
3. You should see output similar to resetting quicklook server. The server stops and restarts in the background.
4. Open Finder, navigate to the file that was showing the wrong preview, and press Space. QuickLook will regenerate the thumbnail from scratch.

If the stale thumbnail persists — which occasionally happens with very large cache databases — add a second step to manually clear the thumbnail cache directory:

1. Run: qlmanage -r cache
2. Then run: rm -rf ~/Library/Caches/com.apple.QuickLook.thumbnailcache
3. Finally restart Finder: killall Finder

macOS will recreate the thumbnailcache directory fresh the next time QuickLook is invoked. You will not lose any files — only the cached previews, which the system regenerates on demand.

Restarting the QuickLook Daemon

QuickLook runs as a per-user daemon called quicklookd. The qlmanage -r command is usually sufficient to restart it, but you can also kill it directly:

• killall -9 QuickLookUIService — targets the UI rendering process on Apple Silicon Macs (macOS 12+).
• killall -9 quicklookd — targets the legacy daemon name still present on Intel Macs and some Rosetta environments.

After killing the process, launchd relaunches it automatically within a few seconds. You do not need to log out or restart your Mac.

QuickLook Cache Size: What to Expect

The cache size depends heavily on the kinds of files you work with. Below is a rough sizing guide based on common workflows.

If you are auditing all the caches that contribute to your System Data figure, the QuickLook cache is just one piece. A tool like Crumb can audit all of these at once and show what is safe to delete before you actually remove anything. You can also read more about what cache files are on a Mac and which ones are worth clearing.

Clearing the QuickLook Cache on macOS Sequoia and Tahoe

The commands above work identically on macOS Sequoia (15.x) and the Tahoe developer betas. Apple has not changed the cache location or the qlmanage tool in recent releases. The main difference on Apple Silicon versus Intel is the process name used for the rendering service (QuickLookUIService versus quicklookd), but qlmanage -r cache handles both correctly without needing to know which chip you have.

If you are running macOS in a managed environment (MDM, corporate profile), verify that your IT policy does not restrict qlmanage before running it. In almost every case it is available and unrestricted for local users.

Other Caches Closely Related to QuickLook

QuickLook does not operate in isolation. Two related caches often show stale previews alongside it:

Finder Icon Cache

Finder stores its own icon cache separately from QuickLook thumbnails. If clearing the QuickLook cache does not fix a wrong icon, try clearing the icon cache as well:

• sudo find /private/var/folders/ -name com.apple.dock.iconcache -exec rm {} \;
• Then restart Dock: killall Dock

Spotlight Metadata Index

Spotlight indexes file metadata and in some cases generates its own thumbnail data. If you have moved or renamed a large folder and previews are wrong across many files at once, rebuilding the Spotlight index for that volume can help: go to System Settings > Siri & Spotlight > Spotlight Privacy, add the folder, wait a moment, then remove it to force a re-index.

For a broader view of what is consuming your storage across all cache layers, the post on how to clear the system cache on Mac walks through each category in depth.

When You Do Not Need to Clear the Cache

Not every wrong-looking thumbnail points to a cache problem. Before clearing anything, check these simpler explanations:

• The file genuinely has not finished saving — some apps write to disk incrementally and the preview reflects an in-progress state.
• You are looking at a file alias or symlink — QuickLook may preview the target rather than the alias.
• The QuickLook plugin for that file type is missing or outdated — for example, opening .sketch or .fig files without the corresponding app installed may yield a generic icon rather than a rendered preview, and no amount of cache clearing will change that.
• iCloud Drive has not fully downloaded the file — the thumbnail reflects the cloud copy, which may be an older version.

In all of these cases clearing the cache is harmless, but the root cause is elsewhere. Address the underlying issue first.