Air Compressor Sizing Guide


Air compressors are very popular among homeowners and professional contractors. They can be used for both business projects and professional projects. Among many other things, they can be used for building projects, in farms, to pump tires and power tools. Before you purchase any type of air compressor, there are certain things you need to know, one of which is about the size of air compressors.

It comes in different sizes, and selecting from this variety depends on the type of project you need it for. If you get the wrong size of air compressor, it’ll end up performing at a higher energy cost per unit of compressed air and even damage the tool it’s used with. Some of the other problems caused by getting the wrong size of air compressor are reduced capacity to power tools, a build-up of rust and sludge, total damage of the air compressor. To avoid these problems, one of the most important things to do before purchasing an air compressor is to think about the workload, method of air distribution, and the air compressor size best suited for your project.

Air compressors work by sucking air into a storage tank until the pressure in the tank rises to a particular limit called the Cut-out pressure. When this pressure limit is reached, the air compressor shuts off, and the air is retained in the tank until it’s needed. It converts stored pressurized air to power. Air compressors are of different types, there’s the rotatory-screw compressor, scroll compressor, turbo compressor, centrifugal compressor, portable and reciprocating compressor. See How to Adjust Cut-out Pressure on Air Compressor?.

How to Determine Air Compressor Size with CFM and PSI

Pneumatic tools use a CFM rating; it is the volume of compressed air required by the tool at a particular pressure. CFM and PSI can determine air compressor sizing. Below are the steps to follow

  1. Write down the CFM requirement needed for all your pneumatic tools. Check your user’s manual for the required value.
  2. Add up the CFM rating of all the tool you plan to use with the air compressor at the same time. Increase this number by 20 to 25% in case you decide to add another tool later or in case of leaks
  3. Find out the maximum PSI needed to run each of the pneumatic tools you plan to use. You don’t need to add up these numbers; all you need is the highest PSI value.
  4. Compare the values gotten from the total CFM and PSI value and compare it with features on the brand you want to get. Another thing to look out for is the tank size and the horsepower; a regular air compressor should be able to collect at least 5 gallons of air per CFM.

Also, see

Air Compressor Maintenance Guide

How to Use An Air Compressor?

Air Compressor Safety Tips

Air Compressor CFM Guide

How to Choose an Air Compressor

Investing in an air compressor is a reasonable decision; however, you need a lot of research before going ahead to purchase one. Below are the other factors you should consider

Piston or Portable Air Compressor

The most common types of air compressors are the piston and the portable air compressor. The piston air compressor is also called the reciprocating air compressor, and it works by using a piston driven by a crankshaft to force air out of the machine. Air from the environment gets sucked into the air compressor; it then flows into the compression tank where it is pressurized by the piston and then discharged to power the tool.

The portable air compressor works like the piston air compressor but is much smaller and can be carried around the house with ease. Unlike the piston, which is used for heavy-duty projects, the portable air compressor is best suited for smaller tasks. Another difference between these two types is that the portable does not have a tank. Choosing between these two depends on the bulkiness of the task at hand. Choose the portable for smaller tasks because it doesn’t have enough power to run big tools.

Tank Size

The size of the tank indicates the amount of air that can be compressed in the air compressor. This means the bigger tanks can hold more air than the smaller ones. We can say the bigger the tank, the more work you’ll get done. You should get a tank size that suits the tools you are using; getting a smaller size may cause the engine to overheat and damage the air compressor. It is advisable to purchase a compressor with a large tank if you have tools that require high pressure and work at a constant rate.


You need to decide where to put your air compressor before purchasing it. If you are getting a stationary air compressor, this is one important factor to consider. You need a large space to station the air compressor because moving it about is almost impossible. There should be a cleared out area in your work station for the air compressor, and if you buy an electrical air compressor, it has to be close to a power outlet. This is unnecessary if you plan to get a portable air compressor since it has wheels that make it easy to be moved around.

Key Features

Some certain features need to be on an air compressor to improve its performance and offer you maximum control. These are

  • Thermal overload switch is used to turn off the air compressor when it overheats. It prevents the air compressor from damage due to overload.
  • Air cooling system keeps the air compressor cool when it is working. Since it operates at high pressure, it tends to produce a lot of heat.
  • Oil-free pump reduces the cost of maintenance. It means you don’t need oil when using the compressor, and it prevents oil and air from mixing.
  • Ball valve drain helps drain the compressor when the air condenses to liquid. It is a type of drain that offers more convenience than regular drains. It protects the air compressor from pinhole leaks and rust.


An air compressor is a multi-purpose tool used for many purposes, from painting to pumping tires and cleaning electronic devices. The size of your air compressor matters a lot, if you get the wrong size, you may damage your tools and the air compressor. Before you purchase an air compressor, take time out to research on the types and models.