The really simple way to check if a file is 32-bit or 64-bit
- Right-click on the executable file you want to check
- Select “Properties”
- Click the tab “Compatibility”
- An example of the dialog box that opens is shown below
- In the section "Compatibility mode" put a check in the box under "Run this program in compatibility mode for:"
- Open the drop-down menu that lists operating systems. If the list begins with Vista, as shown in the graphic, then the file is 64-bit. If the list of operating systems includes Windows XP, then the file is 32-bit.
- Don't forget to uncheck the box under "Run this program in compatibility mode for:"
alternate option if you have Notepad++
- Open the executable in text editor. You might have to drag-and-drop or use the editor's Open...dialog, because Windows doesn't show Open with... option in context menu for executables.
- Check the first printable characters after the first occurrence of PE. This part is most likely to be surrounded by at least some whitespace (could be a lot of it), so it can be easily done visually.
Here is what you're going to find:
x86:
PE L
x64:
PE d†
A word of warning: using default Notepad on big files can be very slow, so better not use it for files larger than a megabyte or few. In my case in took about 30 seconds to display a 12 MiB file. Notepad++, however, was able to display a 120 MiB executable almost instantly.
This is solution might be useful in case you need to inspect a file on a machine you can't install any additional software on.
source:
https://superuser.com/questions/358434/how-to-check-if-a-binary-is-32-or-64-bit-on-windows