You can setup your widget to present the unit of a variable (e.g. °C, °F, km, mm) in different ways.
Under the tab 'Formula', select the option for the origin of the unit that better works for you.
1. Unit from the original variable
This option will get the field 'unit' of the selected variable to present with the value in the widget. If the variable doesn't have a unit, it will be left empty.
2. Unit from variable used in Formula
When setting a Formula in your widget where the source of the formula is based on another variable, this option will use what is stored in the 'unit' of that variable to present in the widget.
This is helpful when you need to build an application that needs to change the output dynamically. For example, users can select the scale they want to see a temperature at among the options: °C, °F, or K.
3. Fixed Unit
If you select this option, you just need to enter the unit that will be displayed. The unit that you entered will be shown even if the variable contains another unit stored in the bucket.