Great question and it's the most asked. I'll get right to the point. The truth is there is no set or correct price for window cleaning. There are a number of factors that determine the final price for window cleaning.   1. Number of windows - Most window cleaning services charge by the window. Pricing per window can be determined by the size and the location.           2. Scope of service - A typical full service window cleaning for a home includes cleaning the interior and exterior glass, cleaning the window track, (the part that the window slides back and forth on) and the screen. This of course is going to be more than just an exterior only window cleaning.     3. Quality service provider -A reputable window cleaning service will have the necessary insurances like liability and workers comp in case there is an accident while on your property. This is for your protection. Insurance costs will figure into the cost of doing business thus affecting the price per window. Hope this helps!