PixelConverter

PixelConverter is a simple application that gives you the possibility to convert px to em in just a few steps. It doesn't include complex options or configuration settings, making it accessible to all types of users, even those less experienced with such software.

No setup required, besides .NET Framework

The entire program's wrapped in a single .exe file that you can copy to a preferred location on the disk or to a USB flash drive, in order to seamlessly run it on any PC with minimum effort.
Just keep in mind that .NET Framework must be installed, since it was developed with the aid of this platform. On the other hand, it doesn't add new entries to your system registry or create files on the disk without your permission.

Simple interface and options

As far as the GUI is concerned, PixelConverter opts for a normal window with a plain and simple structure, showing all options available.
All you have to do type or paste the values in px or pm format, in order to perform the conversion easily. There are three percentage fields available (75%, 87,5% and 100%) to help you make the calculations based on the percentage size specified in the body tag.
There are no other notable options provided by the app. It doesn't implement options for exporting or printing information. However, you can select each converted value and copy it to the Clipboard using the global keyboard shortcut or by opening the right-click menu.

Evaluation and conclusion

It didn't put a strain on the computer's performance in our tests, thanks to the fact that it needed a low amount of CPU and RAM to work properly. No error dialogs popped up and it didn't hang or crash.
On the other hand, PixelConverter comes packed with just a couple of options and doesn't leave room for customization. Nevertheless, you can test it for yourself, since it's free.