@LovesTha @mhoye the hex based conversion covers what I need… 30 mph is about 0x30 km. The other direction is not as trivial but gives a good approximation if you can recall all seven bit numbers in both bases — 64 km “is” 0x40, so 60ish kms are 40 miles.

It gets funky with things like 55 miles as 55 m is not 85 km but 5 needs to be converted separately…