Air compressors are pneumatic devices that convert electrical or motorized energy into pressurized air. Pressurized air can be used for a wide variety of jobs including filling tires, drills, and even spray painting. Air compressors are great for large painting projects like a car or the wall of a large building. Based on our experience we recommend going with an air compressor that holds 30-40 gallons of pressurized air. This ensures you should be able to complete a normal project without waiting for the compressor to recharge. However, if you are on a tighter budget a 20 gallon tank can typically get up to 140 PSI which should be fine for spray painting a wall or car. You may need to take a short break to let the compressor refill with air depending on the amount of paint you are going to use. After researching several brands and testing several models our #1 pick is the craftsman pancake compressor. Based on its durability, 30 gallon tank, and high PSI this model is a no brainer for anyone looking for a quality air compressor. Alternatively, the BOSTITCH is a slightly cheaper and lighter alternative that is easier to move and should would great for all your spray painting projects!