Are these calculations made/provided using metric units in American airports? If not, that's pretty much a death blow against doing them on-aircraft, as any int

Are these calculations made/provided using metric units in American airports? If not, that's pretty much a death blow against doing them on-aircraft, as any international system has to support two different modes of ingesting data. Edit: And even still, international regulations will vary and so the aircraft carrying two different sets of regulations seems complicated I would think?