How To Calculate Air Compressor CFM to kW

People have been asking how to calculate air compressor CFM to KW and we want to help tackle the question. But first and foremost, its essential to understand that CFM and KW are not directly convertible metrics.

CFM refers to Cubic Feet per Minute, which measures the volume of air that is coming out of an air compressor each minute. kW, on the other hand, represents kilowatts or the amount of energy required to power an air compressor.

Comparing CFM to kW is like comparing apples and oranges. But we can take that analogy one step further: where apples and oranges are still related because they are both fruit, CFM and kW are related because they both influence an air compressor’s capabilities.

How To Convert kW To CFM For Air Compressors

According to Air Compressor Guide, you can produce 5-7 CFM of air for every kW produced in industrial air compressor systems. When this is the case, a simple conversion table would look like this:

Power Output (kW)CFM Output
523 - 35
1050 - 70
25125 - 175
50250 - 350
100500 - 700
2501,250 - 1,750

However, this general rule doesn’t hold true when it comes to mobile, rotary screw air compressors. Mobile systems tend to innovate on compact sizes and lightweight equipment—neither of which are as much of a concern with industrial systems. Because mobile air compressors are complex systems with high performing components, they can require more power.

Let’s take a quick look at two of VMAC’s rotary screw products:

ProductEnginePower OutputCFM Output
G30 Gas DriveHonda GX3908.7 kW @ 3,600 rpm30 CFM
D60 Diesel DriveKubota Diesel D90215.2 kW @ 3,600 rpm60 CFM

As you can see, these VMAC systems produce 3-4 CFM per kW produced, rather than the 5-7 CFM delivered in industrial systems.

Outputs are similar when looking at one of VMAC’s direct competitors. Their gas driven rotary screw air compressor uses a Kohler 26.5 HP engine and requires 19.75 kW of power to produce 60-80 CFM. This works out to the same 3-4 CFM per kW output as the VMAC systems.

Keep in mind that the Honda, Kubota and Kohler engines in the examples above are likely capable of producing higher CFM outputs under the right circumstances, but real-world designs put these systems in the 3-4 CFM per kW range. Therefore, a truer estimate of kW to CFM (and vice versa) for mobile, rotary screw air compressor applications is 3-4 CFM per 1 kW.