# 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, it’s 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

As a rule, one kW can generate 3-4 CFM for mobile air compressor applications. Check out the quick reference chart below to see how this impact outputs:

Power Output (kW)CFM Output
515 - 20
1030 - 40
2575 - 100
50150 - 200
100300 - 400
250750 - 1,000

When designing an air compressor system, engineers need to utilize an engine that produces the right amount of kW. Too little and the desired CFM won’t be achieved. Too much and the system costs more than it needs to. Understanding the relationship between kW and CFM helps air compressor engineers choose the right engines for their systems.

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 D90215.2 kW @ 3,600 rpm60 CFM

As you can see, these VMAC systems produce 3-4 CFM per kW produced.

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 with 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 true estimate of kW to CFM (and vice versa) for mobile, rotary screw air compressor applications is 3-4 CFM per 1 kW.