The capacity of your air compressor is measured in Cubic Feet per Minute or CFM. This is generally the most important thing to look at because it tells you how fast your compressor can deliver air – and how much air you need each minute will depend on the tools you are running. So, it’s useful to think about the types of tools you want to run and check the recommended CFM for those tools when you choose your air compressor.

If your compressor is too “small”, it won’t be able to keep up with your demand, and you will need to stop work while it catches up. However, an air compressor with a big receiver can store compressed air. The machine keeps on compressing air even if you take a break from using your tools, and then it stores this compressed air in the receiver. So you might find that a lower capacity compressor is up to the job if you have a big enough receiver.

All of the air tools or accessories that you use require both a certain pressure of air and a particular volume of air to be supplied. As well as CFM and receiver size, the amount of air your compressor produces will depend on the power of the electric motor and the type of compressor fitted.

Pressure is a measurement of force. We measure pressure by comparing it to our normal atmospheric pressure, which is 1 Bar or approximately 15psi. Most air tools etc. operate at a pressure between 2 Bar (30psi) and 6 Bar (90psi). Most car tyres are inflated to between 1.5 – 2 .5 Bar (22 – 35psi). Most air tools including drills, sanders, nailers and chisels etc. will operate at a pressure of 6 Bar (90psi) approximately.

Air pressure is determined by the highest minimum pressure requirement. For example, some tools consume more air than others. Tools such as pneumatic nail-guns and staplers consume smaller amounts of air, while air grinders and sprayers consume larger amounts. Most tools have a usage rating for CFM consumption at a recommended PSI. This can be found on the tool itself or in the owner’s manual supplied by the tool manufacturer.

The notation CFM (Cubic Feet per Minute) refers to a volume of air produced by the air compressor at a given pressure or PSI (Pound per Square Inch). The right size air compressor will meet your needs in two essential areas: airflow (CFM) and pressure (PSI). It’s critical to get a compressor that meets your needs in both areas – otherwise, you risk damage to both your tools and the compressor itself. Always use CFM and PSI specifications from the nameplate on the product.