Center GUI wondow or box in windowed mode

I made a window using:

new Rect ( (Screen.width - (Screen.width/2) ), 100 , 600, 600);

But it doesnt center in windowed mode.

Im trying to make a main menu showing and hiding different windows. Everyone is using different resolution so its important.

Also a good idea would be to use dynamic size of a box and buttons.

for a GUI box(or Label) 600x600 size, you can say that 600 = Screen.height*0.6f so it will be

new Rect(Screen.width*0.5f-Screen.height*0.3f,Screen.height*0.5f-Screen.height*0.3f, Screen.height*0.6f,Screen.height*0.6f)

the start point of your GUI box is at top left corner so the center of it , will be in the center of screen for any screen size**

better than that is

    //adjust your values here to select the desired size for your Box or Label
    //in Play Mode you can see directly your changes after saving script first
	float boxWidth=Screen.height*0.6f;
	float boxHeight=Screen.height*0.6f;
	
	//Now with the given values make the dot for draw start potision(top left corner)
	float startBoxWidth=Screen.width*0.5f - boxWidth*0.5f;
	float startBoxHeight=Screen.height*0.5f - boxHeight*0.5f;
	
	//and finally 
	new Rect(startBoxWidth,startBoxHeight, boxWidth,boxHeight)
	
	//this can be done also for GUI.Label ,Box , Button etc.

First, Screen.width - Screen.width/2 is the same as Screen.width/2…

Second, the position of a Rect specifies the position of its upper left corner. So to center a Rect on the screen, you’d have to subtract half of the Rect’s width from the position.

new Rect(Screen.width/2 - 300, 100, 600, 600);

i’ve trying to accomplish this… i think its not Screen.width/2 - 300

i try to find the math but i comes up with this to make it center of the screen…

new Rect(Screen.width-(Screen.width-300))/2 , Screen.height-(Screen.height-300))/2 , 600,600);

this should makes the box which is 600x600 placed on the center of the screen.
CMIIW…