Talking Kilowatt Hours

We discuss compressed air energy in a universal language, and because of this it is important to understand some basic, yet fundamental calculations. Remembering these details will make assessing any compressed air system a much quicker process, as well as yield results that are able to be compared. 

When we talk about energy, we are necessarily talking about kilowatt hours. Every aspect of our discussion regarding air compressor energy will take place in kilowatt-hours or kWh. 
The following is a simple calculation¹ you can perform to approximate energy usage of air compressors by horsepower in kilowatt hours:

1 HP = 0.746 kW 

Here are some examples of common horsepower-to-kilowatt conversion calculations:

  • 50 HP = 37.3 kW  (50 x 0.746)
  • 100 HP = 74.6 kW  (100 x 0.746)
  • 200 HP = 149.2 kW  (200 x 0.746)

Multiply the horsepower of the air compressor by 0.746 to equal the machine rating in kW.  This is the standard nameplate rating used on CAGI data sheets. This formula is to be used as a rough calculation for the purposes of giving you a general idea about an air compressor's kW usage only. A comprehensive compressed air audit is the only way to achieve an accurate understanding of a compressed air system's energy usage.