Currently in Krita, it is only possible to change the measurement unit (px/mm/inch/etc.) for the rulers. This is not ideal, as working with different formats requires measuring with different units, and having other elements of the program support this, e.g. the grid, can greatly improve its usability.

In GIMP, for example, there is a drop-down menu in the status bar at the bottom, allowing to choose a unit to work with for the rulers and measuring tool. Settings for other tools, such as rectangle selection, have drop-down menus of their own, and the grid can be configured according to different units specifically for a file. This makes measuring things according to other units much easier.

Reproducible: Always