Since this seems to be a point of constant confusion, I thought it is perhaps time to post a very simple explanation, which hopefully will make it clear enough. It is not really
3. Use
ONLY Customize/Units Setup to tell Max/GMax which system of measurement you want to use:
US Standard Quote:Decimal Inches
Fractional Feet
Decimal Feet
Feet with Fractional Inches
Feet with Decimal Inches
Metric Quote:Centimeters
Meters
Kilometers
You can even change your modeling units as often as you wish while working on the same scene!
If I need a box 1 meter square, I set the modeling units to "Metric:Meters" and simply create the box typing in 1m in the keyboard entry fields.
If I then need a box that is 12" square, I set the modeling units to "US Standard:Inches" and type 12" in the keyboard entry fields.
If I need a plane that is 46.356 feet square, I set the modeling units to "US Standard:Decimal Feet" and type 46.365' in the keyboard entry fields.
On the other hand, if I need to create a plane that is 2.43 hectares or 1.64 acres...
...NOW I need to do some manual calculations!!!