Ductulator vs CaptiveAire Toolbox

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. Privacy Policy: https://docs.google.com/document/d/1r9oCuYYtQZlKWhZTlrP8Ck73V6NoR8lx82027oWszsA/edit?usp=sharing Terms of Service: https://docs.google.com/document/d/1MAY_7_uIVMnf4QYSpeaaSaSV7cm3-TJApqYVLfTHQ7w/edit?usp=sharing

The CaptiveAire Toolbox puts 40+ HVAC and building-systems engineering calculators in your pocket. Designed for engineers, contractors, and technicians, every formula uses standard industry references (ASHRAE, AMCA, NEC), sized so you can run sanity checks in the field instead of pulling out a laptop. Cooling: Total Cooling Load (enthalpy-based with humidity), Sensible Cooling Load, Latent Cooling Load, SEER, Cost of Cooling, Tons to BTU/hr conversions, DX/MPU Cooling, Evaporative Cooling, DMUA mode logic, Cooling Density Factor. Heating: BTU output for direct and indirect fired heaters, Input and Output BTU/hr for IBT systems, Temperature Rise from BTU and CFM, Heat Pump capacity with airflow and outdoor temperature adjustment, Reheat Coil leaving conditions, Manifold Pressure for natural gas and LP, Heating Density Factor. Ventilation and Airflow: Room Volume CFM, Sensible Heat CFM, Cooling Load CFM, Duct Velocity CFM, Outdoor Air Load (sensible plus latent), Psychrometric properties from dry bulb plus RH or wet bulb, Fan Energy Index per AMCA 208, Motor Adjusted Frequency for VFDs, ERV ROI Calculator with degree-day economics. Electrical Sizing: Wire Size per NEC Table, MCA and MOCP for motor circuits, Amperage from horsepower. Piping and Structural: Round Duct Sizing using Darcy-Weisbach and Colebrook-White, Duct Velocity and Friction, Piping Pressure Drop with fittings equivalent length, Pitched Roof curb height variation. Valve and Flow Sizing: Kv from flow rate, flow rate from Kv, pressure drop from Kv, Cv to Kv conversion, Heat Load to Flow Rate for water and glycol. Reference: ASHRAE Weather Station data with autocomplete address search, returning heating and cooling design temperatures, solar irradiance, wind speeds, and monthly design-day temperatures. Interactive Psychrometric Chart with property calculations. Modern HVAC versus Traditional Rooftop Unit comparison. Each calculator includes the formula and variable definitions accessible from the title bar. Tap the info icon to see exactly what equation drives the result. Built by the engineering team at CaptiveAire Systems. No tracking, no ads, no account required.