Duct Calc

About this app

Duct Calculator is a professional HVAC engineering tool designed to calculate airflow, air velocity, and duct sizes for both rectangular and circular ducts. The app is built for HVAC technicians, ducting engineers, MEP consultants, site engineers, and students who need fast and accurate duct sizing and airflow calculations on site or during design. This application supports both Metric and Imperial units with automatic internal unit conversion, ensuring reliable and consistent results for real-world HVAC design and verification work. Available Calculators: Air Flow Rate Calculator (CFM / m³/h) Air Velocity Calculator (FPM / m/s) Duct Size Calculator (Rectangular and Circular) Air Flow Rate Calculator: This calculator determines airflow based on duct size and air velocity. It supports rectangular and circular ducts and displays results in CFM for Imperial units and m³/h for Metric units. Air Velocity Calculator: This calculator determines air velocity from known airflow and duct dimensions. Results are displayed in FPM (Imperial) and m/s (Metric), making it useful for checking duct performance and noise limits. Duct Size Calculator: This calculator determines required duct dimensions based on desired airflow and target air velocity. It provides: Rectangular duct size (length × width) Circular duct diameter Duct Type Support: Users can switch between rectangular and circular ducts. The app automatically applies the correct formulas for each duct type. Smart Unit Handling: Full Metric and Imperial unit support Automatic unit conversion Results displayed in industry-standard units No internet connection required Key Features: HVAC duct sizing calculator Airflow and air velocity calculation Rectangular and circular duct support Metric and Imperial unit systems Accurate engineering formulas Clean and simple interface Fast and reliable on-site calculations Duct Calculator is ideal for HVAC engineers, mechanical engineers, site supervisors, duct fabricators, MEP consultants, and engineering students. It helps reduce manual calculation errors and speeds up HVAC duct design and verification work in real-world applications.

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1. First observed Aug 16, 2026 · 6:35 AM $2.99