Game view always 2x size of Screen?

Hi there. I’m fairly new to Unity and I’m working in 2D with an orthographic view.
I’m trying to dynamically position some objects. However no matter how I look at my camera I can’t figure out why a BoxCollider2D with a size converted from Screen.width and Screen.height to world coordinates would not take up the whole screen.

I’m using Standalone(1024x768). I switch to full screen on run and try to re-size the collider in the object’s Update() with the following code:

BoxCollider2D box = GetComponent<BoxCollider2D>();
Vector3 screenSize = Camera.main.ScreenToWorldPoint (new Vector3(Screen.width, Screen.height, -10));
box.size = new Vector2(screenSize.x, screenSize.y);

However the resulting box takes up exactly half of the blue area in the GameView when I’m expecting it to take up the whole thing. The same can be said for Free Aspect mode. The box still takes up exactly half. Is this due to some camera setting or is it just part of Unity?

Well to get to Vector3(0, 0, z) for example you would need to take the centre of the screen:

Camera.main.ScreenToWorldPoint (new Vector3(Screen.width/2, Screen.height/2, 10));

So to get the full screensize you probably need to do:

Camera.main.ScreenToWorldPoint (new Vector3(Screen.width, Screen.height, -10))-Camera.main.ScreenToWorldPoint (new Vector3(0, 0, -10));