Can I upgrade from Windows 7 32 bit to windows 7 64 bit?

No. In-place upgrades are never possible when switching architectures

abhijit_reddevil said:

Hi,

Please tell me whether I can upgrade from Windows 7 32 bit to Windows 7 64 bit without doing a clean install (just with the upgrade option).

Click to expand...

No. If you are currently running a 32-bit version of Windows, you can only perform an upgrade to another 32-bit version of Windows. Similarly, if you are running a 64-bit version of Windows, you can only perform an upgrade to another 64-bit version of Windows.

If you want to move from a 32-bit version of Windows to a 64-bit version of Windows Vista or vice versa, you'll need to back up your files and then choose the Custom option during Windows Vista installation. Then, you'll need to restore your files and reinstall your programs.

source: 32-bit and 64-bit Windows: frequently asked questions

Yep, not possible.

no it is not possible to upgrade from 32 bit to 64 bit without clean installation.

Ok...guess I will have to backup my files then and then do a clean install. Thanks for your inputs, anyway.

practically and theoretically both its just impossible.

No ways without a Clean installation. Without clean install you may switch to other 32 bit editions. Not 64 bit