Painting Job Estimator for Painters. Painting Job Estimator is for interior rooms. Enter room size to calculate square footage and perimeter of room. Save your interior painting estimates and customers data. The application saves your item prices in settings and adds up your painting estimate automatically. It also calculates how much paint and or wallpaper you need to do the job. Paint Job Estimator allows you to accurately bid on a painting project. It will work on cell phones as well as tablets.