Replacing just the glass (a “glass-only” or sash replacement) is usually cheaper than replacing the entire window unit. Glass replacement typically costs $100 to $400 per pane, depending on size, glass type, and whether it’s insulated or specialty glass.
Full window replacement, including frame, hardware, and installation, generally runs $300 to $1,200 or more per window.
Glass-only replacement makes sense if the frame is in good condition and only the glass is cracked, foggy, or broken. If the frame is rotted, warped, or inefficient, full replacement often pays off long term through better insulation and lower energy bills.