Duct Calculator - HVAC Sizing
HVAC duct sizing
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
Size ductwork in seconds. Enter airflow (CFM) and air velocity (FPM) to get round and rectangular duct dimensions on the spot. Built for HVAC work in the field.
Duct Calculator is a focused duct sizing tool for HVAC engineers, designers and installation technicians. Enter what you know and get the duct dimensions, airflow or air velocity you need, without a chart or a slide rule.
CALCULATIONS
- Duct size: find the required duct dimensions from airflow (CFM) and air velocity (FPM).
- Airflow: determine the airflow rate in CFM.
- Air velocity: determine velocity in FPM to help verify system performance.
DUCT SHAPES
- Round ducts
- Rectangular ducts
- Results shown in inches
WHO IT IS FOR
- HVAC engineers and designers checking a duct size during design work.
- Installation technicians and contractors who need a quick answer on site.
- Students learning how airflow, velocity and duct size relate.
WHERE IT HELPS
- Sizing a new supply or return run from a known CFM.
- Checking whether an existing duct keeps velocity within your target.
- Comparing a round duct with a rectangular one when space is tight.
SIMPLE BY DESIGN
A clean interface with only the inputs you need, so you get an answer quickly on the job.
Duct Calculator is free to use. An optional one-time upgrade removes ads.
Results are intended as a calculation aid. Always confirm designs against applicable codes and project requirements.
Download Duct Calculator and size your next duct run.
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Ratings & Reviews
• Improved overall performance and stability
• Fixed minor bugs and enhanced user experience
The developer, Sachinbhai Surani, 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
- Sachinbhai Surani
- Size
- 46.6 MB
- Category
- Productivity
- Compatibility
Requires iOS 15.6 or later.
- iPhone
Requires iOS 15.6 or later. - iPad
Requires iPadOS 15.6 or later. - iPod touch
Requires iOS 15.6 or later. - Mac
Requires macOS 12.5 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Contains
Advertising
- In-App Purchases
Yes
- Lifetime premium $9.99
- Copyright
- © 2025