"Ought to", perhaps, but aren't (isn't?). It depends very much on the unit and the value being measured: in the UK, °C have been used on weather forecasts for years, and I think most of us are familiar with them (to the extent that when I recently heard a forecast in °F I was totally flummoxed), yet for body temperature? It's still pretty much °F - at least, I wouldn't have much idea of what counted as "dangerous" in °C - and I have difficulties in marrying up the two (okay, I know you can subtract 32, divide by 9 and multiply by 5 or whatever it is, but I don't do it on a regular basis). And then, of course, there are the Americans, who still seem to judge everything in °F, so again your target market is important. Oven temperatures are another thing: some recipes use °F, others °C, and it seems to me that most don't give both any more (I use gas, so don't pay too much attention). Mileage, again: I don't think many Brits have any great concept of distance/speed in kilometres, and I'm pretty sure that speedometer dials on UK cars still show miles as the main unit, and km in a secondary position.On the question of kilometre-mile conversions, I'm going to be severe with the "Anglo-Saxon" community (horrible term). I feel that, in translation to English, metric units, °C etc. should be maintained because they are international units and by now everybody ought to be familiar with them.
Yes, that's true, although I suppose technically that's localisation as much as translation - and do you round up, down, or give an exact figure? Again, that's going to depend on the target and purpose of the text. But UK weights and measures are no longer solely metric: we only recently got some sort of dispensation, from the EU, I assume, to go on using the avoirdupois system. It's so much easier to ask for a quarter of something than two-hundred-and-fifty-whatever gramsOn the other hand, in translating from English, miles and °F are not international units and will sooner or later disappear (in GB now all weights and measures are metric and °C have been used for decades), so they need to be translated.