HVAC

Fan CFM Calculator

Calculate airflow (CFM) from duct size and air velocity, size ventilation using ACH, estimate CFM from heat load and temperature change, and convert airflow units.

CFM FPM ACH m³/h

Airflow Sizing & Fan CFM Estimator

Use duct area and velocity, room ACH targets, or heat-load rules to size airflow. Includes unit conversion and CSV export.

Solve For

Duct Shape

Diameter

Diameter Unit

Width

Height

Width/Height Unit

Velocity

Velocity Unit

Airflow

Airflow Unit

Room Dimension Unit

Length

Width

Height

Target ACH

Given Fan Airflow (optional)

Given Airflow Unit

Heat Load

Heat Load Unit

Temperature Change (ΔT)

ΔT Unit

Method

Air Density ρ (kg/m³)

Specific Heat Cp (J/kg·K)

Sizing Table

Export

Value

From Unit

To Unit

Fan CFM Calculator

Airflow Sizing & Fan CFM Estimator

Duct Area

Airflow

Velocity

m³/h

L/s

Equation Used

Room Volume

Required Airflow

Required m³/h

Achieved ACH

Rule Used

Notes

Required Airflow

m³/h

L/s

Equation Used

Inputs Summary

Reminder

Converted

CFM

m³/h

L/s

m³/s

Conversion Basis