Hi All this may be old news to some but i found two realy good scale conversion Apps on Android(goole play)
Quisk scaler pro is a free app thats allows you to quickly scale various measurements of verious units great for us model makers.
There other App is from Woodland Scenics called model scaler this covers a wide rangs of scale as well as letting you place in a custom scale.
I find them usefull and i hope you all do to