How Do I Size a Piston Compressor for my workshop?

Learn how to properly size your piston compressor based on your needs

Air compressors should be sized based on the volume of air (cfm/m3h) and air pressure (psi/bar) needed to do the job and not horse power. Single stage air compressors have a maximum pressure of around 130 psi (9 bar) while two stage air compressors have a maxinum air pressure of 175 psi (12 bar). Tank size is typically not a critical factor in sizing a compressor.

Calculating your need

  1. What is the maximum pressure you need? (refer to the table below for a general guideline)
  2. What is the electrical requirements (voltage/phase)?
  3. How many people will be using air at any time (maximum)?
  4. Is this a body shop or mechanical shop?
    1. Body Shop: 12-15 cfm/person X # of people
    2. Mechanical Shop: 3-5 cfm/person X # of people
  5. Now add at least 25% to your total cfm required in order to allow for duty cycle.


Typical cfm consumption by tool

Tool/Equipment Air Pressure (psi) Air Pressure (bar) Air Consumed (cfm) Air Consumed (l/s)
Impact Wrench 3/8-1/2 70-90 4.8-6.2 5 2.36
Impact Wrench 1/2-3/4 70-90 4.8-6.2 10 4.72
Impact Wrench 3/4-1 3/4 70-90 4.8-6.2 20 9.44
Air Ratchet 70-90 4.8-6.2 3-5 1.42-2.36
Body Sander (Oribital) 70-90 4.8-6.2 12 5.66
Tire Changer 125-150 8.6-10.3 2 0.94
Bead Breaker 125-150 8.6-10.3 12 5.66
Blow Gun 70-90 4.8-6.2 3 1.42
Die Grinder 70-90 4.8-6.2 7 3.3
Screwdriver #2-6 Screw 70-90 4.8-6.2 5 2.36
Screwdriver #6-5/16 Screw 70-90 4.8-6.2 10 4.72
Paint Spray Gun (Touch Up) 70-90 4.8-6.2 4 1.89
Paint Spray Gun (HVLP) 40-60 2.7-4.1 15 7.08
Nailers/Staplers 70-90 4.8-6.2 2-4 0.94-1.89
Chart intended as a reference only. Actual air consumption may vary.

    Tool/Equipment Air Pressure (psi) Air Pressure (bar) Air Consumed (cfm) Air Consumed (l/s)
    8.6-10.3
    Chart intended as a reference only. Actual air consumption may vary.

      Tool/Equipment Air Pressure (psi) Air Pressure (bar) Air Consumed (cfm) Air Consumed (l/s)
      8.6-10.3
      Chart intended as a reference only. Actual air consumption may vary.
      Thank you CP Compressors for this video.

      Do you have an idea for our #expertcorner? Let us know!

      Useful links:

      Book Your Compressor Service

      Who we are and how Ash Air can help your business!

      Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!

      • Reciprocating, Screw, air compressors
      • Vacuum pumps
      • Nitrogen
      • An extensive line of air treatment components

      Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.

      Reliability and Efficiency

      With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our efforts on the following:

      • Increasing uptime
      • Reducing unexpected repairs
      • Reducing energy consumption
      • Improving the cleanliness of compressed air


      Talk to the team today:  CONTACT US CONTACT US

      Read more from our #expertcorner


      When it comes to laser cutting and other industrial processes, the choice of assist gas is crucial in achieving optimal results. Nitrogen and oxygen are commonly utilized as assist gases, each with its own unique properties and applications. Understanding the characteristics of both gases, will help you to make an informed decision to ensure precision, efficiency, and cost-effectiveness in your operations. …

      Show More