>>96220948
Anyway, to answer your question, nobody questions lizardmen using the exact same units of measurement as humans because they're usually close enough together. The fact that you're usually not having to travel to the exact opposite end of the world to visit them means that you can excuse them understanding what your measurements are and how it converts to their system.

tl;dr - In-universe everyone is assumed to know it through proximity, and no Players want to waste time with the conversions anyway.