If you want your exports from Blender to be the same size as objects in Unity then you need to export your FBX files as follows:
- Go to: File > Export > FBX.
- Set your FBX export settings as shown in the picture below.
- Make sure that option 2 in the picture is disabled.
- Now you can hit that export button without worrying about the size differences.
As a test you could export a cube(1m3) from Blender and import it in Unity. Create a cube in Unity, put the Unity cube and the exported cube next to each other and you’ll see that they are the same size.
When you export more complex objects from Blender you’ll notice that they are not rotated correctly in Unity. Here is an example of a building I was working on. When I imported it in Unity it looked like this:
I know you can rotate the thing in Unity and be done with it. For some reason it kept bugging me so I looked into it. I found out trough a post on the Unity forum that if you rotate your object in Blender -90 degrees on the X axis and apply the rotation to the object(CTRL+A), it will be rotated correctly in Unity. Below you can see the same building in Blender after I’ve rotated it.
After you apply the rotation, the rotation will be reset to 0. To make it easier to modify the object just rotate the object 90 degrees on the X axis but don’t apply the rotation. Below you can see the final result in Unity.