Air Compressor Buying Guide

Air Compressor Performance Ratings

When matching a pneumatic tool's requirements to an air compressor's capabilities, the most important rating to consider is how much air the compressor can deliver, which is measured in standard cubic feet per minute (SCFM). Tools powered by air compressors also have SCFM ratings, which indicate the air flow required for optimal operation.

The actual SCFM changes depends on the pressure of the air in the compressor, which is represented as pounds per square inch (psi). Look for the "SCFM at 90-psi" number when comparing SCFM ratings.

Smaller tools usually require between 0- to 5-SCFM, while larger tools can require 10- or more SCFM. To gauge the minimum compressor SCFM rating you need, examine the SCFM requirements of all the tools you intend to use. Multiply the highest tool rating by 1.5 to get the minimum compressor SCFM for your needs. This gives you a little buffer, which is important, since actual SCFM varies during compressor operation.

If you expect to operate multiple pneumatic tools at the same time, you'll need more power. In this case, calculate the minimum SCFM compressor rating by adding up the SCFM requirements for each tool that you'll use simultaneously. Most light-duty home compressors are designed to power only one tool at a time, but larger professional-grade compressors can handle multiple tools.

The air pressure the compressor generates inside the tank is measured in psi. Light-duty compressors generally have 90-psi, which is typically sufficient for pneumatic tools for simple household tasks, including nailers. More powerful compressors may generate 150-psi or higher.

While not as important as the SCFM rating, a compressor's horsepower (HP) rating can give you a relative sense of the model's power. Horsepower indicates how powerful the motor is, while the SCFM rating tells you how much power the compressor actually provides to your tools. Compressors generally have horsepower ratings between 1 1/2- to 6 1/2-HP.