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HVAC Air Duct Sizing & Velocity Calculator (CFM / m³/h)

HVAC air conditioning and industrial ventilation engineering tool. Computes duct sizing adhering to ASHRAE standards to limit aerodynamic noise.

Input Parameters

Required Airflow Rate (Q in CFM)

Recommended Velocity (v in FPM)

Instant Calculation Result

Estimated Output

Active in Real-Time

Adjust values on the left to calculate live results.

Formula: Duct Area (ft²) = Flow (CFM) / Velocity (FPM). Circular Diameter D (in) = sqrt((4 * Area_ft² * 144) / π).

In-Depth Guide & Mathematical Methodology

🌀 ASHRAE Air Duct Velocity Limits

Residential Main Ducts: 700 - 900 FPM (low noise)

Commercial Main Ducts: 1,000 - 1,500 FPM

Industrial Ducts: 1,500 - 2,200 FPM

Frequently Asked Questions (FAQ)

What is the HVAC Air Duct Sizing & Velocity Calculator (CFM / m³/h) and how does it work?

HVAC air conditioning and industrial ventilation engineering tool. Computes duct sizing adhering to ASHRAE standards to limit aerodynamic noise.

How do I use this HVAC Air Duct Sizing & Velocity Calculator (CFM / m³/h)?

Enter Required Airflow Rate ($Q$ in CFM - Cubic Feet per Minute). Select Recommended Air Velocity ($v$ in FPM - Feet per Minute, e.g. 800 FPM residential). View Required Circular Diameter (inches and mm) and Duct Section Area.

What mathematical formula is used in this calculation?

Duct Area (ft²) = Flow (CFM) / Velocity (FPM). Circular Diameter D (in) = sqrt((4 * Area_ft² * 144) / π).

Is the HVAC Air Duct Sizing & Velocity Calculator (CFM / m³/h) on FindCalculator free to use?

Yes, all 330+ interactive tools on FindCalculator.online are 100% free, run directly in your browser without registration, and do not store your private calculation data.

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