Installing the right size pipes in your compressed air system can be crucial in minimizing the effects of pressure drop. You must ensure you install the right sized air pipes for this reason, and so, calculating the correct pipe size at the start of your project can help you save a lot of money in the future.

This article will provide you with a CFM pipe size chart that can be used as a guideline for when you are selecting the right pipe sizes for your system.

Table of Contents

CFM Pipe Size Chart

Let’s get straight into it, the following chart will help you gain a better understanding of the pipe size you need depending on the volume of airflow you have running through it, and its length!

Air Flow (CFM)Pipe Length (feet) 25Pipe Length (feet) 50Pipe Length (feet) 75Pipe Length (feet) 100Pipe Length (feet) 150Pipe Length (feet) 200Pipe Length (feet) 250
5½½½½½½½
10½½½½½½½
15½½½½¾¾¾
20½½¾¾¾¾¾
25½¾¾¾¾11
30½¾¾¾111
35¾¾¾1111
40¾¾¾1111
45¾¾11111 ¼
50¾11111 ¼1 ¼
55¾1111 ¼1 ¼1 ¼
60¾1111 ¼1 ¼1 ¼
65¾1111 ¼1 ¼1 ¼
70¾111 ¼1 ¼1 ¼1 ¼
75111 ¼1 ¼1 ¼1 ¼1 ¼
80111 ¼1 ¼1 ¼1 ¼1 ¼
85111 ¼1 ¼1 ¼1 ¼1 ¼
90111 ¼1 ¼1 ¼1 ¼1 ½
9511 ¼1 ¼1 ¼1 ¼1 ¼1 ½
10011 ¼1 ¼1 ¼1 ¼1 ½1 ½

CFM Pipe Size Discussion

In a compressed air system, any pressure losses that are greater than 3% are considered excessive and so, when designing the system, users typically try to ensure that the system has a maximum loss of around 1%. Well-designed systems will have a steady rate of airflow and aim to lose only 1 PSI for a system that is at 100 PSI.

Any kind of obstruction in a compressed air system can lead to a pressure drop. Things like flexible hoses, pipe length, quick-connect and other types of couplings, filters, regulators, lubricators, and other components are all going to cause pressure drop. Therefore, you must select the right size pipe to ensure you can minimize the pressure drop as much as possible.

As can be observed in the chart, the pipe size in inches depends not only on the volume of air in CFM (Cubic Feet per Minute) flowing through it but also on how far that air must be carried. Typically, to ensure that the distribution loss is not greater than 1%, or 1 PSI, the greater the length of piping, the greater the diameter of the pipe needed to carry the same flow as a smaller pipe on a shorter length of pipe.

The chart represents a 100 PSI compressed air system designed to transport the flow of air with less than a 1 PSI loss. If you had a system carrying 110 PSI then these pipe sizes will carry more air than is indicated in the chart, or the pressure loss will be even lower. If the system was carrying 90 PSI, then the pipe sizes will carry less air than indicated.

The left column in the chart represents the volume of air that is to be carried through the system, in CFM. It is difficult to estimate the amount of airflow volume flowing through each system as it will vary depending on the application. Some distribution systems will have many air-operated machines and tools operating off many legs like in a factory or plant setting. Here, the flow should be at a fairly steady rate, compared to a smaller system that has a high surge of air and then a period of almost no flow.

Determining Your Pipe Size – Tips

In order for you to choose the correct diameter of the pipe for your air compressor system, you need to know how much flow rate (CFM) you intend to have traveling through your pipe, and how long the pipe will be. You must remember when choosing your diameter, that the larger the size the greater the airflow. But, this will drive the costs of the system up so you should size your air compressor system based upon the tools you use.

Optimum flow rate systems are typically installed as a loop, where they start at the air compressor and loop around the shop or garage back to the compressor as in the example below. Doing so, increases flow rate and decreases pressure drop across the whole system. Which will allow you to use smaller diameter pipes.

The thread size of the port on your air compressor tank outlet does not determine the size of your pipe for your system, a very common misconception. You calculate the pipe size using your desired length and the air compressor CFM output. Even with the air compressor tank outlet port being small because the air is only traveling a short distance so the restriction is minimal.

Finally, I would like to leave you with some tips to help you with your pipe size considerations:

  • Compressed air becomes restricted over long distances
  • Flow rate decreases the further it is from the compressor
  • Larger pipe sizes increase air flow but also costs
  • Longer distances require large pipe diameters
  • Sizing down piping at the end of a run decreases flow rate and offers no benefits

FAQs (Frequently Asked Questions)

How much CFM can a 1/2 pipe flow?

A 1/2″ pipe can have anything up to 10 CFM of an airflow across lengths of pipe up to 250 feet. You may even be able to have up to 30 CFM flowing through a 1/2″ pipe, but only for lengths of pipe up to 25 feet.

How do I know what size compressed air pipe to use?

To know what size compressed air pipe you need, you must know the length of your intended system and the CFM you intend to flow through. With these two values, you can refer to an air compressor pipe size chart to get the correct size piping for your system.


If you have any questions regarding CFM pipe size, please leave a comment below, with a photo if applicable, so that someone can help you!