HVAC Duct Calculator

Quick HVAC duct, airflow, grille and diffuser checks with Metric SI and US inch units.

HVAC Duct Calculator is a practical engineering calculation tool for quick ventilation and duct sizing checks.

Use it during design reviews, field checks, early estimates, and technical training when you need fast preliminary calculations for HVAC ductwork and air terminals.

Key calculations:

• Duct calculation Calculate air velocity, friction loss, and equivalent round duct diameter from airflow and duct dimensions.

• Duct shapes Run preliminary checks for rectangular, round, and oval duct options.

• Airflow and air change calculation Estimate required airflow from room dimensions and air change values, with results in m3/h and L/s.

• Grille, louver, and diffuser checks Check face velocity using airflow, dimensions, and free area/effective area ratio.

• Unit systems Work with Metric SI or US inch units.

• Sharing Share calculation results through the native iOS share sheet.

Who it is for:

• Mechanical engineers
• HVAC design teams
• Site and commissioning teams
• Technicians
• Ventilation and air-conditioning professionals
• Students who need preliminary technical checks

The app does not include ads, account signup, or subscriptions. Core calculation tools are free. An optional one-time VIP unlock can enable advanced local workflow tools such as duct takeoff, quick sizing, saved records, and professional helper screens.

Important note: This app is designed for information and preliminary calculation only. Results are not a substitute for final engineering design, manufacturing, installation, code compliance, or professional judgment. Always verify results with applicable standards, manufacturer data, project specifications, and a qualified engineer.

For feedback, suggestions, or bug reports, use the support options inside the app.