Is There a way to get the right setting resolution for game window while editing ?

If I set the output with a resolustion like 480x800，the screen.size just get the window editor frame size which means it changes depend on the size of my editor window. That's meaningless. I need the setting resolustion(480x800)
I can't find any api to solve this.(like I found screen.currentresolustion.width which gives me the pc screen resolution)

Why I need this even I know the reslution would be right after published.But how I see effect my game while editing in unity.
I hope there should be a way.
Thanks.