64-bit Firefox is the new default on 64-bit Windows
Users on 64-bit Windows who download Firefox will now get our 64-bit version by default. That means they’ll install a more secure version of Firefox, one that also crashes a whole lot less. How much less? In our tests so far, 64-bit Firefox reduced crashes by 39% on machines with 4GB of RAM or more
64-bit Firefox has more security and fewer crashes
What’s the difference between 32-bit and 64-bit?
Here’s the key thing to know: 64-bit applications can access more memory and are less likely to crash than 32-bit applications. Also, with the jump from 32 to 64 bits, a security feature called Address Space Layout Randomization (ASLR) works better to protect you from attackers.
macOS and Linux users, fret not. You already enjoy a Firefox that’s optimized for 64-bit.
How do you get 64-bit Firefox?
If you’re running 64-bit Windows (here’s how to check), you have two options to get your computer hooked up with this improved Firefox experience:
You can download Firefox now and reinstall, which will automatically install Firefox 64-bit; or
You can wait. We intend to migrate the remaining 64-bit Windows users to a 64-bit version of Firefox with a future release. If you prefer to stay with 32-bit Firefox after the 64-bit migration, you can simply download and re-run the Firefox 32-bit installer from the Firefox platforms and languages download page.