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How can I tell if this is a 32 bit or a 64 bit browser?

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While trying to install Java Runtime Environment Plugin, I was asked this:

Which Download should I choose?

Choose the 32-bit download to use with a 32-bit browser. Choose the 64-bit download to use with a 64-bit browser. If you use 32-bit and 64-bit browsers, you need to download both 32-bit and 64-bit Java.

So, how do I know if this is a 32 bit or a 64 bit browser?

While trying to install Java Runtime Environment Plugin, I was asked this: Which Download should I choose? Choose the 32-bit download to use with a 32-bit browser. Choose the 64-bit download to use with a 64-bit browser. If you use 32-bit and 64-bit browsers, you need to download both 32-bit and 64-bit Java. So, how do I know if this is a 32 bit or a 64 bit browser?

Chosen solution

Firefox Releases from mozilla.org including the current 37.0.2 is still Win32.

So for Win32 firefox you need 32-bit Plugins.

The Firefox 38.0 may be the first release to have Win64 builds along with Win32.

The WOW64 in your Firefox useragent shows it is a Win32 application on 64-bit Windows.

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Chosen Solution

Firefox Releases from mozilla.org including the current 37.0.2 is still Win32.

So for Win32 firefox you need 32-bit Plugins.

The Firefox 38.0 may be the first release to have Win64 builds along with Win32.

The WOW64 in your Firefox useragent shows it is a Win32 application on 64-bit Windows.

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Most probably your browser is 32 bit unless you have downloaded an unofficial build of firefox.

An easy way to find out whether an application is 64 or 32-bit to check the installation folder:

   (all 32-bit applications will be here:) C:\Program Files (x86)\
   (all 64-bit applications will be here:) C:\Program Files\