Duct Flow Calc HVAC Tool2026

Duct Flow Calc is an offline utility for HVAC and ventilation field work. It helps you quickly calculate airflow, air velocity, duct size, and round-to-rectangular duct equivalence. All data is stored only on your device. No login, no network connection, and no user data collection are required. Core features: 1. Convert airflow, velocity, and cross-sectional area with common unit switching. 2. Recommend rectangular duct sizes and derive width-height combinations from a target velocity. 3. Convert between circular and rectangular equivalent ducts for easier design comparison. 4. Estimate simple resistance and show velocity range hints to reduce field sizing mistakes. 5. Save local project records, including rooms, floors, system numbers, and calculation results. This app is suitable for HVAC design assistants, site engineers, ventilation installers, and cost estimators working on construction sites, plant rooms, and field surveys without reliable internet access.