How to get dialog size?

Give it a try:

mDialog.getWindow().getDecorView().getHeight() 

Actually, in Android it doesn't work like in iOS - you can't get the size of the View itself, what you can do, though, is to ask for the size of the ROOT layout of that view.

e.g.:

myDialog.this.findViewById(R.id.dialog_root_layout).getHeight());