Some homeowners who use air compressor tools only need a small, portable compressor unit that pushes about five cubic feet of air per minute. The air tools powered by compressors of this size include impact wrenches and brad nailers, good for plenty of jobs in the garage and in the house. If you need larger air tools such as polishers and sanders, you'll need a larger air compressor that can push at least ten cubic feet per minute or CFM. When picking an air compressor to power your air tools, be sure to check the PSI (pounds per square inch) as well as the cubic feet per minute. Larger tools may require a compressor capable of up to 120 PSI. When deciding on the compressor, check your tools first, then check the capacity of the compressor. You'll save yourself a trip or two back to the hardware store if you write down the CFM and PSI needs of your air tools before shopping.