The cost of painting a house interior varies; it depends on the size of the house, the type of paint, and the number of coats of paint. If you're wondering how much does it cost to paint a room, you should know that it's between $100 and $300 to paint a room on average. However, if you don't feel comfortable taking on this job yourself, it's best to hire a house painter, although it will end up costing you more.