HVAC Duct Calculator

CFM

CFMCalculator.net

Calculate duct size, velocity, and pressure drop for HVAC systems.

Calculation Formula:

Area: \( \pi \times \left(\frac{\text{Diameter}}{2}\right)^2 \)
Velocity: \( \frac{\text{CFM}}{\text{Area}} \)
Pressure Drop: \( \text{Friction Rate} \times \left(\frac{\text{Duct Length}}{100}\right) \)

Airflow (CFM):

Velocity (FPM):

Duct Shape:

Diameter (inches):

Friction Rate (in. w.g. /100 ft.):

Duct Length (ft):

Number of Elbows:

Elbow Type:

Area (sq. in.):

Velocity (FPM):

Diameter/Dimensions (inches):

Total Pressure Drop (in. w.g.):