Drilling Tools

• An air drill with a 3/8-inch chuck capacity will require 4 to 7 cubic feet of air per minute (CFM) to operate. An air-powered drill with 1/2-inch capacity will require 6 to 8 CFM at 90 pounds per square inch (PSI).
  
  

Grinding Tools

• A grinder with the power to operate a 7-inch grinding disc will use an average of 7 CFM at an air pressure of 90 PSI.
  
  

Chiseling Tools

• One of the more common air tools is the air chisel. It requires an average of 4 to 8 CFM at 90 PSI. Needle scalers are similar tools and require the same approximate CFM.
  
  

Mechanics Tools

• The most commonly used mechanic's air tool is the impact wrench. For automotive use, a 1/2-inch drive impact wrench is the most popular and will require about 5 CFM. Larger 3/4-inch wrenches for truck use require 8 to 11 CFM for proper operation. A larger air hose is also required.
  
  

Sizing the Compressor

• While CFM delivery is of primary importance, the maximum pressure and storage tank size are important also. Select a compressor with a CFM output at least 25 percent greater than what is required by the number of tools which will be operated at the same time. If given a choice, buy your shop compressor with the largest tank capacity available.