Duct Calculator
Duct Size Calculator
Convert Rectangular Duct to Round Equivalent
Convert Round Duct to Rectangular Equivalent
Duct Size Calculator
The Duct Size Calculator allows HVAC contractors to quickly determine the appropriate duct size based on airflow and velocity, essential for efficient system design and installation.
Inputs:
- Air Flow (CFM - Cubic Feet per Minute): This is the volume of air the system needs to move.
- Air Velocity (FPM - Feet per Minute): The speed at which the air moves through the duct.
How It Works:
- The contractor inputs the CFM (airflow) and FPM (velocity) values.
- The calculator computes the duct's required cross-sectional area in square feet using the formula:
Area (sq ft) = CFM / FPM - To determine the circular duct size, it calculates the diameter using the area:
Diameter (inches) = 2 × √(Area / π) × 12 - For rectangular ducts, the calculator assumes a 2:1 aspect ratio (width: height) and computes both dimensions:
Width = √(Area × 2), Height = Width / 2
Additional Conversion Options:
- Convert Rectangular to Round Duct: Given the dimensions of a rectangular duct, the equivalent circular diameter is calculated using a standard conversion formula.
- Convert Round to Rectangular Duct: Based on the diameter of a round duct, contractors can enter one rectangular side dimension to find the other.
Disclaimer:
The calculations provided by these HVAC calculators are intended to serve as estimates and recommendations made in good faith based on standard industry practices. While efforts have been made to ensure accuracy, these results may not account for all variables, and inaccuracies may occur.
For precise calculations and optimal system design, it is strongly recommended to consult a qualified HVAC design engineer who can take into account the specific requirements and conditions of your project.
Use these tools at your own discretion and always double-check the results with a professional before making significant decisions regarding HVAC installations or modifications.