Air Duct Size Calculator
Pressure Drop & Friction Rate
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Size round and rectangular ducts, check pressure drop, compare equivalent conversions, and review airflow calculations with clear engineering detail.
Air Duct Size Calculator is a focused HVAC tool for professionals who need fast duct sizing, airflow checks, and clear pressure-related calculations. It is built for practical work: direct input, clear results, and quick access to the engineering values behind each calculation.
Use it to size round and rectangular ducts from airflow with either a target velocity or a target friction rate. You can review exact results, compare practical rounded sizes, and work through realistic options without relying only on a traditional ductulator workflow. The app also lets you analyze an existing duct, solve section pressure-drop relationships, estimate run loss, and compare round and rectangular conversions in one place.
Key capabilities:
• Size round and rectangular ducts by velocity or friction
• Analyze an existing duct from airflow, velocity, or friction
• Solve pressure-drop relationships for total pressure drop, friction rate, straight length, or added equivalent length
• Estimate run loss using straight length, equivalent length, fitting loss coefficient K, and allowable-loss checks
• Convert round to rectangular and rectangular to round
• View equal-area references alongside equivalent conversions
Built for practical HVAC work:
• Imperial and metric defaults
• Airflow units including CFM, CFS, m³/s, L/s, and m³/h
• Velocity, dimension, length, temperature, friction, and pressure unit controls
• Fractional inch support for dimensions
• Material presets, including flexible duct options with correction support
• Local settings persistence on device
When you need more than a quick answer, engineering detail stays visible. The app can show Reynolds number, Darcy friction factor, dynamic pressure, hydraulic diameter, equivalent round diameter, air density, and dynamic viscosity, so you can see the values behind the result instead of treating it like a black box.
Engineering details include:
• Reynolds number
• Darcy friction factor
• Dynamic pressure
• Hydraulic diameter
• Equivalent round diameter
• Air density
• Dynamic viscosity
Air Duct Size Calculator is intentionally focused on duct sizing, duct analysis, pressure-drop workflow, and equivalent conversion. It is not presented as a full network design suite, report export tool, fitting database, or cloud project system.
If you need a practical duct calculator with transparent assumptions and a clean workflow, Air Duct Size Calculator is built for that job.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
UI Improvements
The developer, Alona Nesterenko, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Alona Nesterenko
- Size
- 2.9 MB
- Category
- Utilities
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Lifetime Access $1.99
- Copyright
- © 2026 Alona Nesterenko
