Duct Sizer Calc HVAC
Utilities
$0.99 · In‑App Purchases · Designed for iPad. Not verified for macOS.
HVAC Duct Sizing Calculator is the professional duct sizing tool for HVAC technicians, engineers, and contractors. Calculate correct ductwork dimensions based on airflow (CFM), velocity, or friction rate using ASHRAE standard sizes and ACCA Manual D methodology - the industry standard for professional air conditioning system design.
SIZING METHODS:
CFM-Based Method - Enter airflow and get recommended standard duct sizes instantly
Velocity-Based Method - Size ducts by target air velocity (FPM) for proper sizing
Friction Rate Method - Default 0.08 in. w.g. per 100 ft or custom pressure drop values
DUCT TYPE SUPPORT:
Round Duct Sizing - Calculate diameter based on CFM and friction loss
Rectangular Equivalent - Find standard rectangular dimensions for any round size
Flex Duct Correction - Automatic 10% correction factor for flexible ductwork
All Standard Sizes - Results snap to ASHRAE industry-standard dimensions
ADVANCED CALCULATIONS:
Velocity Check - Ensures airflow stays within safe limits (optimal 400-900 FPM)
Pressure Drop Analysis - Darcy-Weisbach calculation per 100 ft of duct
Reynolds Number - Full hydraulic analysis for precision engineering
Friction Loss Display - See calculated friction for every result
OPTIONAL PRO UPGRADE — $2.99 ONE-TIME IN-APP PURCHASE
The following features require a separate one-time in-app purchase. They are not required to use the calculator:
• Unlimited saved calculation history
• PDF export of results
• Dark theme
• Ad-free experience
WHY HVAC PROS USE THIS CALCULATOR:
Faster ductwork design than manual slide rules and ACCA charts
ASHRAE-compliant and Manual D-verified sizing ensures proper system performance
Cross-check velocity and friction rate for perfectly balanced systems
Prevents over/undersized ducts that reduce efficiency and increase noise
Field calculations without internet connection needed on job sites
PERFECT FOR:
HVAC design engineers planning new installations
HVAC technicians calculating duct replacement sizing
HVAC field technicians verifying existing ductwork
AC contractors preparing accurate job estimates
HVAC students learning Manual D design methodology
Residential and commercial HVAC system design
Based on ACCA Manual D constant friction method and ASHRAE Handbook fundamentals.
Part of HVACTools Suite - the complete HVAC technician app for field calculations, refrigeration tools, and air conditioning diagnostics.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
What's new:
- Friction loss now follows the ASHRAE friction-chart equation (was understated up to 2x)
- Added Reynolds number and a color-coded Manual D velocity check (400-900 FPM)
- Round sizes extended to 48 in; rectangular equivalents recalculated per the ASHRAE Huebscher equation
The developer, Rizvan Adzhoian, 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 Used to Track You
The following data may be used to track you across apps and websites owned by other companies:
- Identifiers
Data Not Linked to You
The following data may be collected but it is not linked to your identity:
- Identifiers
- Usage Data
- Diagnostics
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Rizvan Adzhoian
- Size
- 35.3 MB
- Category
- Utilities
- Compatibility
Requires iOS 13.0 or later.
- iPhone
Requires iOS 13.0 or later. - iPad
Requires iPadOS 13.0 or later. - iPod touch
Requires iOS 13.0 or later. - Mac
Requires macOS 11.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
18+
- 18+
- Contains
Advertising
- In-App Purchases
Yes
- Pro Unlock $2.99
- Copyright
- © 2026 Rizvan Adzhoian