Does Unity use Meters or Centimeters as is default Unit Size:
1 unit = 1 meter
or
1 unit = 1 centimeters
I want to always have my imported models show a scale factor of 1 (I Think)… When is use a FBX Exporter and set to centimeters the scale factor for that model says 0.010 (And it shows up really small and i have to use the scale to make bigger).
Should i always set FBX Exporter to save my model in meters or centimeters?
1 Unit = 1 Meter
Tip: Just because your imported model has a scale of 1,1,1 doesn’t mean that it’s one meter in diameter. The Unity cube primitive is one meter tall by default. So if your model should be one meter tall in real life, make it match the height of a Unity cube. 
Is there a way to select both the cube and my model and ask unity to make the same size (scale) ?
There are a couple of ways to handle the scale of an object in Unity:
1). Simply drag your model into the scene, put a Unity cube beside it, and use the scale tool to match the 1 meter tall object to the cube’s height. This is a per object method.
2). Go into the model’s FBX import tab and change the scale factor until it matches the cube size. This is a per object method.
3). The best way (and the one I use) is to go into your 3d graphics program and modify the FBX export scale factor (usually under preferences of some sort) and change it so that a cube exported from your 3d graphics program is the same size as a cube in Unity.
With number three, all of your models will be correct scale for Unity.
If i edit the model in maya… how do i tell if it is the same size as cube in unity since they wont be sitting next to each other…
You make a cube in Maya and compare the model to the cube since the Maya cube will be the same size as a Unity cube.
So if your model is supposed to be a meter stick, simply scale it in Maya to match the size of a primitive cube in Maya.
Ok so I don’t have a problem getting a model into unity from Maya and getting it to the right size. What I am noticing is when I import an FBX say a box 1 meter from Maya then I set the scale factor in the import settings to 1 to match Maya. The box ends up the correct size, but in the inspector the xyz scales all show 0.01. If I leave the scale Factor at 0.01 then I have to set all the xyz scales to 1.
Either way works, but which way is the best? My concern is on performance. Someone mentioned somewhere about performance on objects that are out of scale. I can’t remember why exactly. Something about just another thing for the engine to calculate.
I noticed that too… I cant say which is best, being a Unity3D noob…
But i set the FBX Importer scale to 1 and just change the xyz on the GameObject in the scene view.