How to Clear the Firefox Cache on a Mac (and Why It's Safe to Delete)
~/Library/Caches/FirefoxYes, the Firefox cache is safe to delete. It lives at ~/Library/Caches/Firefox and holds temporary copies of web content that Firefox rebuilds automatically as you browse. Your bookmarks, passwords, history, and extensions are stored in a different folder entirely, so none of that is at risk. The only cost is that sites load slightly slower on your first visit after clearing.
What it is
~/Library/Caches/Firefox is where Firefox keeps its disk cache on macOS. Inside you'll find a Profiles folder with one subfolder per Firefox profile, and inside each of those a cache2 directory. That cache2 directory holds the actual cached files: images, scripts, stylesheets, fonts, and chunks of pages you've already visited. When you return to a site, Firefox pulls these from disk instead of downloading them again, which is why pages you visit often feel faster.
The folder grows as you browse, but Firefox manages its own ceiling. With the default automatic cache management, the disk cache usually lands in the hundreds of megabytes and rarely goes much past a gigabyte or two per profile. If you have multiple profiles, each one keeps its own cache, so the totals add up. It is a scratch area by design: everything in it is a copy of something that exists on the web and can be fetched again.
Is it safe to delete?
Deleting this folder loses you nothing permanent. Every file in it is a local copy of web content, and Firefox recreates the folder structure the next time it launches. The one thing you give up is warm-cache speed: for a day or so, sites you visit will re-download their images and scripts, so first loads are a bit slower and you use a little more bandwidth. After that, things feel normal again because the cache has refilled.
The important distinction is between this folder and ~/Library/Application Support/Firefox. The Caches folder is disposable. The Application Support folder holds your actual profile: bookmarks, saved passwords, history, cookies, and extensions. Don't confuse the two. As long as you're deleting under ~/Library/Caches, you're only throwing away copies. Diskmack identifies the Firefox cache automatically and clears it the safe way, without touching your profile data.
How to check its size
In Finder: In Finder, choose Go > Go to Folder (or press Shift+Command+G), paste ~/Library/Caches and press Return. Select the Firefox folder in the list and press Command+I to see its size in the Get Info window.
In Terminal:
du -sh ~/Library/Caches/FirefoxHow to clean it
- Quit Firefox completely with Command+Q. Don't just close the window; deleting cache files while the browser is running can cause errors.
- In Finder, press Shift+Command+G, paste ~/Library/Caches and press Return.
- Select the Firefox folder and press Command+Delete to move it to the Trash.
- Empty the Trash, then reopen Firefox. It recreates the cache folder on launch and starts refilling it as you browse.
If you'd rather stay inside the browser, open Firefox's Settings > Privacy & Security > Cookies and Site Data > Clear Data, and check only "Temporary cached files and pages." Leave cookies unchecked so you stay signed in to your sites.
Will it come back?
Yes, and quickly. Re-caching is the whole point: Firefox starts writing to the folder again the moment you resume browsing, and within a few days of normal use it will be back near its usual size. That's fine. The cache manages its own upper limit, so it won't grow without bound. Treat clearing it as a one-time space recovery when your disk is full, not a lasting fix. If the same folder keeps eating space you can't spare, the real answer is more free disk, not more frequent clearing.
Common questions
Will deleting the Firefox cache remove my bookmarks, passwords, or history?
No. Those live in your profile folder at ~/Library/Application Support/Firefox/Profiles, which is a completely separate location. Deleting ~/Library/Caches/Firefox only removes temporary copies of web content.
Will I get logged out of websites?
No. Logins are stored in cookies, which live in your profile folder, not the cache. The exception is if you use Firefox's Clear Data dialog and also check the cookies box; leave it unchecked and your sessions survive.
Firefox is still using a lot of disk space after I cleared the cache. Why?
Check ~/Library/Application Support/Firefox. Site data like offline storage, your extensions, and the profile database all live there and can outweigh the cache. That folder holds your actual data, so don't bulk-delete it. If a specific site is hoarding space, clear its storage from Settings > Privacy & Security > Cookies and Site Data > Manage Data.
How big does the Firefox cache get?
Firefox limits it automatically. Most people see a few hundred megabytes, and heavy browsing on a profile can push it past a gigabyte. Each Firefox profile keeps its own cache, so several profiles mean several caches.