What clearing the cache does

Clearing the cache removes temporary files that Firefox stores on your computer — images, scripts, and partial web pages that the browser saves so sites load faster the next time you visit. When you clear it, Firefox deletes those files and starts fresh. The next time you visit a site, it downloads everything again, which takes a few seconds longer, but you see the newest version of that page instead of an outdated copy.

Most people clear the cache when a website looks broken, loads incorrectly, or shows old information even after refreshing. It also frees up disk space, though usually not much — most caches are under 500 megabytes unless you have not cleared it in years.

Key Takeaways

  • Open Firefox, press Ctrl+Shift+Delete (Windows) or Command+Shift+Delete (Mac), and the cache-clearing window opens when ready.
  • Select "Cached Web Content" in the dropdown, choose how far back to clear (usually "Everything"), and click "Clear Now".
  • Clearing the cache does not delete your passwords, bookmarks, or browsing history unless you specifically check those boxes.
  • If a site still looks wrong after clearing the cache, try opening it in a private window to rule out other stored data.

The keyboard shortcut method (fastest)

Press Ctrl+Shift+Delete on Windows or Command+Shift+Delete on Mac. The "Clear Recent History" window opens when ready. At the top, you will see a dropdown that says "Time range to clear" — leave it set to "Everything" unless you only want to clear the last hour or day. Below that, uncheck everything except "Cached Web Content" — this prevents you from accidentally deleting passwords or browsing history.

Click the blue "Clear Now" button. Firefox removes the cache files and closes the window. You are done. The next time you visit a website, it will load the current version from the internet instead of showing you what Firefox had stored.

The menu method (if the shortcut does not work)

If the keyboard shortcut does not open the window, use the menu instead. Click the three horizontal lines (hamburger menu) in the top right corner of Firefox. Select "Settings" from the dropdown. On the left side, click "Privacy & Security". Scroll down until you see the "Cookies and Site Data" section.

Click the button that says "Clear Data". A small window appears. Make sure "Cached Web Content" is checked and everything else is unchecked. Click "Clear". Firefox removes the cache and closes the window.

What not to clear by accident

When the cache-clearing window opens, you will see checkboxes for several types of data: cookies, site data, browsing history, downloads, and more. Leave all of these unchecked unless you specifically want to delete them. Clearing cookies and site data will log you out of websites. Clearing browsing history removes the list of sites you have visited. Clearing downloads removes the record of files you downloaded, though the files themselves stay on your computer.

If you only want to clear the cache, check only "Cached Web Content" and nothing else. This is the safest approach and takes the same amount of time.

When clearing the cache actually solves the problem

A stale cache causes specific problems: a website shows outdated information, buttons do not work, images do not load, or the layout looks broken. Clearing the cache fixes these because Firefox downloads a fresh copy of everything. If you clear the cache and the problem persists, the issue is something else — a problem with your internet connection, an extension that is interfering, or a real problem on the website itself.

If you want to test whether the cache is the problem without clearing it permanently, open the site in a private window (Ctrl+Shift+P on Windows, Command+Shift+P on Mac). Private windows do not use the cache at all. If the site works correctly in private mode, the cache was the problem. If it still looks wrong, clearing the cache will not help.

How often you should clear it

You do not need to clear the cache on a schedule. Clear it only when a website looks wrong or when you want to free up disk space. Some people clear it every month, others only when they notice a problem. There is no performance benefit to clearing it regularly — Firefox manages the cache automatically and deletes old files when it gets too large.

If you want Firefox to clear the cache automatically every time you close the browser, go to Settings, click "Privacy & Security", scroll to "Cookies and Site Data", and check the box that says "Delete cookies and site data when Firefox is closed". This does not affect your passwords or bookmarks, only the cache and cookies.

Frequently Asked Questions

Will clearing the cache delete my passwords?

No. Passwords are stored separately from the cache. When you clear the cache, Firefox only removes temporary files. Your saved passwords stay in place unless you specifically check the "Logins and Passwords" box in the clearing window, which you should not do unless you want to delete them.

Why does a website still look wrong after I cleared the cache?

The problem might be cookies or site data instead of the cache. Try clearing those as well: open the clearing window, check both "Cookies and Site Data" and "Cached Web Content", and click "Clear Now". If it still does not work, try the site in a private window. If it works there, an extension is probably the problem.

How much disk space does the cache use?

Usually between 100 and 500 megabytes, depending on how long it has been since you last cleared it and how much you browse. You can see the exact size in Settings under "Privacy & Security" in the "Cookies and Site Data" section — it shows "Cached Web Content" with a size next to it.

Can I clear the cache for just one website?

Not easily. The cache-clearing tool removes all cached files at once. If you want to clear cache for one site only, open it in a private window instead, which bypasses the cache entirely. Or clear the entire cache and then visit the sites you use most so Firefox rebuilds their cache.