How to give height from bottom instead of top

I have GUI.Label to display some content. I know new Rect(10, 50, 100, 20). The 50 is reduce from Top Margin. I need to reduce the height from bottom of 50. Where to change the code?

GUI.Label(new Rect(10, 10, 100, 20), "Hello World!");

Not sure if I understand your question, but if you you mean the Y position of the rect, then this would place it 50 pixels above the screen bottom

GUI.Label(new Rect(10, Screen.height - 50, 100, 20), "Hello World!");

Hope this helps.

Use Screen.width and Screen.height:

GUI.Label(10,Screen.height-50,100,20), "Hi");