Duct Calculator - DuctCalc

The only app combining professional duct sizing with psychrometric calculations. ASHRAE-compliant formulas. Imperial & Metric units. Used by HVAC engineers worldwide.

Professional HVAC duct sizing and psychrometric calculations in one powerful app. DuctCalc replaces your physical ductulator with a modern, accurate digital tool trusted by engineers, contractors, and HVAC professionals.

DUCT SIZING CALCULATOR

Size round, rectangular, and flexible ductwork with ASHRAE-compliant calculations:

• Forward Mode: Enter CFM airflow → Get multiple duct size options with velocity, friction loss, and pressure drop for each • Reverse Mode: Select a duct size → See CFM capacity at minimum, ideal, and maximum velocities

Supports 6 duct materials:

• Galvanized Steel
• Flex Duct (extended & compressed)
• Duct Board
• Fiberglass Lined
• PVC/Plastic

FITTINGS & PRESSURE DROP

Calculate total equivalent length and pressure loss with 10+ standard fittings:

• 90° and 45° Elbows (smooth, 3-piece, mitered)
• Tees (branch and straight-through)
• Reducers and Transitions
• Takeoffs (90° and 45°)
• Register Boots

PSYCHROMETRIC CALCULATOR

Complete humid air property analysis with interactive chart:

• 4 Input Modes: Dry bulb + wet bulb, relative humidity, dew point, or humidity ratio • Calculates: Enthalpy, specific volume, vapor pressure, saturation pressure, degree of saturation • Altitude correction for non-standard atmospheric pressure • Visual psychrometric chart showing current state point

APPLICATION TYPES

Pre-configured velocity limits per ASHRAE/ACCA guidelines:

• Residential Supply (400-1000 FPM)
• Residential Return (300-800 FPM)
• Commercial Low Velocity (600-1500 FPM)
• Commercial High Velocity (1000-2500 FPM)

PROFESSIONAL FEATURES

Imperial (I-P) and Metric (SI) units Airflow in CFM, m³/h, or L/s Color-coded status indicators Real-time validation warnings Built-in reference documentation Standard duct size tables (ASHRAE/SMACNA)

WHY DUCTCALC?

Unlike other apps that only size ducts OR calculate psychrometrics, DuctCalc combines both essential HVAC tools. No more switching between apps. Professional-grade accuracy in your pocket.

Perfect for: • HVAC Engineers • Mechanical Contractors • MEP Design Firms • HVAC Technicians • Building Inspectors • Engineering Students

Download DuctCalc and replace your old ductulator with the modern HVAC calculator trusted by professionals.

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