Window cleaning might cost a homeowner typically $200, with small jobs priced at $91 and around $367 for large houses with a lot of windows in difficult to reach areas. Some of the common factors that contribute to the cost of a window cleaning service are the number of windows, the screens, sills and tracks, and mineral deposits. Some window cleaning in Wilmington services charge by the number of windows to be cleaned, while others by the square footage of the window. If the window has a screen, that needs to be cleaned too, and will incur additional charge. Sills and tracks are sometimes neglected by homeowners when cleaning their window. A professional can do the task with the cost to be included on the bill. Mineral deposits in windows require the attention of professionals. They normally need special solutions to be removed and that can add up to the cost of the cleaning process.