CFM to kW Calculator

Convert airflow (CFM) to power (kW, HP) using static pressure and fan efficiency. Calculate power requirements for fans, blowers, and HVAC systems.

Fan Power Calculator:

Calculate the power required to move air at a given flow rate and pressure. Perfect for HVAC design, industrial ventilation, and fan selection.

CFM to kW Converter

Mode

Volume flow rate of air

100 CFM 20,000 CFM

Resistance the fan must overcome

%

Typical range: 50-85% (check manufacturer specs)

Calculation Results

Enter airflow and pressure

then click "Calculate" for power

CFM to kW Calculator

Converting CFM (cubic feet per minute) to kilowatts helps you determine the power needed to run fans and blowers. This calculation is essential for selecting the right motor size for HVAC systems, industrial ventilation, and exhaust applications.

Quick Tip

A fan moving 2000 CFM at 2 inches of water gauge with 70% efficiency requires about 0.90 kW. If you increase efficiency to 85%, the same airflow needs only 0.74 kW — saving energy costs over time.

What is CFM to kW Conversion?

CFM measures how much air flows through a system each minute. Kilowatts measure the electrical power needed to move that air. The conversion between them depends on two key factors: the pressure the fan must overcome and how efficiently the fan operates.

When you know these values, you can calculate the motor size needed for your application. This prevents undersizing (motors that overheat and fail) or oversizing (wasted money and energy).

Formulas Used

CFM to kW (Air Power)
kW = (CFM × Pressure_inWG × 0.000157) ÷ Efficiency
The constant 0.000157 converts CFM × inches of water gauge to kilowatts of air power.
CFM to HP (Horsepower)
HP = (CFM × Pressure_inWG) ÷ (6356 × Efficiency)
The constant 6356 is derived from converting units based on standard air density.
Reverse: kW to CFM
CFM = (kW × Efficiency) ÷ (Pressure_inWG × 0.000157)
Use this when you know the motor size and need to find the airflow capacity.

How to Use This Calculator

Enter your airflow requirement in CFM (or other units), the static pressure the fan must overcome, and the fan efficiency percentage. The calculator shows the power needed in kilowatts, horsepower, and watts.

For more accurate results, enable Engineering Mode to adjust for temperature and altitude. These factors affect air density, which changes the power required to move air.

CFM to kW Reference Table

This table shows power requirements for various airflow and pressure combinations at different efficiencies:

Airflow (CFM) Pressure (inWG) Efficiency Power (kW) Power (HP)
100 0.5 60% 0.013 0.018
250 1.0 65% 0.060 0.081
500 1.0 65% 0.121 0.162
750 1.5 70% 0.252 0.338
1000 1.5 70% 0.336 0.450
1500 2.0 70% 0.672 0.901
2000 2.0 70% 0.896 1.201
2500 2.5 75% 1.308 1.753
3000 2.5 75% 1.570 2.104
4000 3.0 75% 2.509 3.364
5000 3.0 75% 3.137 4.205
6000 3.5 80% 4.118 5.520
7500 3.5 80% 5.147 6.900
8000 4.0 80% 6.274 8.409
10000 4.0 80% 7.843 10.512
12000 4.5 82% 10.337 13.858
15000 4.5 82% 12.921 17.322
18000 5.0 85% 16.624 22.284
20000 5.0 85% 18.471 24.760
25000 5.5 85% 25.368 34.000
30000 6.0 85% 33.165 44.456
40000 6.0 85% 44.220 59.274
50000 6.5 85% 60.029 80.458