How do I tell if I have the 32-bit or 64-bit Firefox?

This article only applies to Firefox on Windows.

Both 32-bit and 64-bit versions of Firefox are available for 64-bit operating systems, on Windows 7 and above. See this blog post to learn more about 64-bit Firefox. If you want to switch to the 64-bit version of Firefox, see How to switch from 32-bit to 64-bit Firefox.

Not sure whether you're running 32-bit or 64-bit Firefox? This article explains how to find out.

About Firefox window

You can find what version of Firefox you are using in the About Firefox window. Click the Firefox menu button New Fx Menu , click help Help-29 and select About Firefox. (32-bit) or (64-bit) will be shown under the Firefox name, after the version number.

Note: Opening the About Firefox window will, by default, start an update check. If an updated version of Firefox is available, it will be automatically downloaded. For more information, see Update Firefox to the latest version.

User agent

The user agent identifies your browser to websites and contains information about your operating system and browser version. This can be an easy way to identify which version of Firefox is running.

To find your user agent, click the Firefox menu button New Fx Menu , click help Help-29 and select Troubleshooting Information. This will open the Troubleshooting Information page.


In the Application Basics section of this page, find the User Agent entry and look at the information enclosed within the parentheses.

If you seeWhat it means
Win64; x6464-bit Firefox
WOW6432-bit Firefox on 64-bit Windows
(neither of the above)You're running 32-bit Windows and it will not run 64-bit Firefox

Windows program listing

You can also check the installed version of Firefox from the Windows list of installed programs. Open the Windows Control Panel, click on Programs, then Programs and Features.Open Windows Settings, click on System, then Apps & features. This will show you a list of software that is currently installed on your computer.

To see if the 32-bit or 64-bit version of Firefox is installed, locate Mozilla Firefox in the list of programs. The program name will include the Firefox version and, in parentheses, the bit version and language. If the program name contains x86, the 32-bit version of Firefox is installed. If the program name contains x64, the 64-bit version of Firefox is installed.
Note: You can have both 32-bit and 64-bit Firefox program versions listed, if you installed one version without uninstalling the other. If you don't want both you can uninstall the unwanted version. The Firefox uninstaller doesn't remove any of your Firefox user data such as passwords or bookmarks.

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