Chrome does not showing width of screen as screen resize?

This question may be very simple. Usually as we inspect an element and we re-size browser ,browser automatically shows the width of screen.Currently i am using chrome but as i inspect any element it does not show width height of screen.I am making a site responsive but my browser not showing any screen size so i am in trouble .I seach for it but i have not found any result .I also did restores default and reload from setting but it has no effect.Any help would be highly appreciated