Calculator in Windows 10 comes with a lot of useful features like conversion between different units of measurements (weight, temperature, area, time, data storage, speed etc), programmer mode and so on.
Using these features is simple. First, change the mode from Standard to any of the conversion functions visible on the list.
Next, enter the input values along with original units of measurements and change the output unit to what is needed.
The results for these will be shown in a cool format.
The Programmer mode allows conversion between various number systems along with other features.
So there is no need to use any external tool to convert units since all of this is well covered in the Windows 10 calculator. However, for other operating systems, a portable and small desktop tool for units conversion may come in handy.