Real World Measure units to Maya units
 

I was wondering what the real world equivilant to the grid in Maya is depending on the given zoom layer (It doesnt matter which layer).

I just want to know where to start when I want to make a room 20' x 20' How does that translate into the Maya unit of measure. Are those inches, cm, Can they be changed? Should they not be changed for the sake of continuity?

go to windows/settings preferences/preferences/settings and you can set the grid unit to represent what you want (cm,meters,feet inches ect).

It is then your choice what scale you make the model but there is no problem making a model 1:1 even if its 200ft x 100ft

You can work in real world measurements using the grids.
https://www.youtube.com/watch?v=YF1sEN9B1CA
This will explain it.