Of course, this process might differ from one company to another, but we believe it would give you a good general idea on how painters come up with a quote. Step 1: Measuring and counting what needs painting, including all related prep work and clean up. It includes measuring the size of the rooms to be painted, including all surfaces such as doors, kitchen cabinets, trims, etc. Step 2: Calculating how much time and resources are needed to complete the project. Step 3: Adding the cost of paint and materials.