Bmp2Icon

Bmp2Icon is a tiny and portable software utility with a very simple purpose in mind: it lets you convert bitmap images to .ICO format, so you can assign them as icons to your favorite applications.
It doesn't integrate complex options or configuration parameters, making it accessible to all types of users.

No setup necessary

Since this is a portable tool, you can save its executable file anywhere on the disk and just click it to launch Bmp2Icon. Another possibility is to save it to a removable storage unit to directly run it on any PC with minimum effort and no previous installers.
More importantly, it doesn't modify Windows registry settings, so it doesn't increase the risk of OS stability issues.

Simple interface and options

Made from a small window that implements an Explorer-based folder structure for rapidly navigating disk directories to locate .bmp-formatted images, the interface is clean and intuitive.
You can preview a selected photo within the main window, specify the output icon size between 16x16, 32x32, 48x48 and 64x64 pixels, indicate the output directory and file name, and proceed with the conversion operation with one click, as Bmp2Icon takes care of the rest. There are no other notable options provided by this piece of software.

Observations and conclusion

Unfortunately, it doesn't feature batch processing support, so you are restricted to converting only one photo at a time. The app hasn't been updated for a long time, and we've noticed that it has compatibility issues with newer OS editions (we tested it on Windows 7).
Conversion jobs were carried out rapidly while the app remained light on system resources. It didn't hang, crash or display errors during this time.
All in all, Bmp2Icon offers a straightforward solution to creating icon files with predefined sizes from bitmap images, so you can give it a shot.