Firefox for Android and iPhone stores cached pages, images, cookies, and site data that build up as you browse. You can clear it from inside Firefox on both platforms, and on Android you can also clear the cache through system Settings.
Short answer:
- In Firefox (both platforms): Menu (three dots) > Settings > Delete browsing data > choose Cached images and files, then Delete.
- Android system: Settings > Apps > Firefox > Storage & cache > Clear cache (safe).
- Clearing cookies and site data logs you out of websites; clearing cache alone does not.
- iPhone: use the in-app Delete browsing data option or reinstall Firefox.
What Firefox Stores on Your Phone
As you browse, Firefox caches page resources, images, and scripts so sites reload faster. It also stores cookies, site data, browsing history, saved logins, and downloads. Over time, cached files and downloads are usually what take the most space.
The key distinction: clearing cached images and files is safe and only forces sites to reload fresh, while clearing cookies and site data signs you out of websites and resets site preferences. Choose what you delete deliberately.
Clear Browsing Data Inside Firefox (Android & iPhone)
Firefox's own controls work the same way on both platforms and give you precise choices.
- Open Firefox and tap the menu (three dots; bottom-right on iPhone, top-right on Android).
- Tap Settings.
- Scroll to Delete browsing data (on iPhone it may read Data Management).
- Tick Cached images and files for a safe space recovery. Leave Cookies and site data unticked if you want to stay logged in.
- Tap Delete browsing data to confirm.
To do this automatically, enable Delete browsing data on quit in the same menu so Firefox clears your chosen categories every time you close it.
Clear the Firefox Cache on Android via Settings
Android lets you clear Firefox's cache from the system storage screen, which is thorough.
- Open Settings > Apps.
- Tap Firefox.
- Tap Storage & cache.
- Tap Clear cache.
This removes temporary files without logging you out of websites or deleting your bookmarks. The space is reclaimed immediately.
Caution: the same screen has Clear storage (or Clear data). That wipes Firefox to a fresh install, deleting cookies, saved logins not synced to a Firefox Account, history, and settings. Use it only if the browser is broken. The clear cache vs clear data guide explains exactly what each removes, and how to clear app cache on Android safely covers the routine.
Clear Firefox Storage on iPhone
iOS has no per-app cache button, so rely on the in-app option first.
- Use Firefox > Settings > Data Management to delete Cache and, optionally, cookies and downloads.
- If the app still shows a large footprint, delete and reinstall Firefox from the App Store. Sign in to your Firefox Account afterward to restore bookmarks, history, and saved logins.
A Clenoir storage scan shows how much space Firefox and other apps actually use on iPhone, with a review-first flow so you confirm every deletion.
Manage Downloads and Keep Firefox Lean
Downloads often outweigh the cache itself.
- Tap the menu > Downloads to review and delete saved PDFs, images, and files.
- Sign in to a Firefox Account so bookmarks and logins sync to the cloud, making a reinstall painless.
- Clear cached images and files once a month if you browse heavily.
If your phone is still tight on space after cleaning Firefox, the browser is rarely the main culprit; photos and video usually are. For a wider sweep, see the clean up phone storage hub, which walks through the heaviest categories on a typical phone. Clearing Firefox's cache is safe, quick, and keeps mobile browsing fast.
Tabs, Sync, and Other Hidden Space
A few less obvious habits keep Firefox slim over time. Open tabs themselves cache page content, so closing the dozens of tabs you forgot about frees memory and a little storage. Use the tab tray's overflow menu and choose Close all tabs when the count climbs into the hundreds.
If you use Firefox Sync, your open tabs, history, and logins follow you between devices, which means a reinstall is genuinely painless: install the app, sign in, and everything returns. That makes the "delete and reinstall" purge the most thorough option without any real downside. Just confirm sync is enabled under Settings > Account before you uninstall, so nothing important lives only on the device you are about to wipe.
Finally, review any extensions you have added on Firefox for Android. Add-ons cache their own data, and ones you no longer use are dead weight; remove them from Settings > Add-ons. Between clearing the cache, trimming downloads, and pruning tabs and extensions, Firefox stays fast and small on any phone.
FAQ
How do I clear the cache in Firefox on my phone?
Open Firefox, tap the menu (three dots), tap Settings, then Delete browsing data (or Data Management on iPhone). Tick Cached images and files, leave Cookies and site data unticked to stay logged in, then tap Delete browsing data.
Does clearing Firefox's cache log me out of websites?
No. Clearing cached images and files only forces sites to reload fresh. It is clearing cookies and site data that signs you out of websites and resets site preferences, so choose what you delete deliberately.
How can I make Firefox clear its cache automatically on mobile?
Enable Delete browsing data on quit in the same Settings menu, and Firefox will clear your chosen categories every time you close it.