DuctPro
HVAC Duct Sizing Calculator
Free · Designed for iPad. Not verified for macOS.
DuctPro is the professional HVAC duct sizing calculator built for field technicians and MEP engineers. Get engineering-grade results in seconds — offline, no subscription.
RESULTS IN 3 TAPS
Enter airflow, select duct type, get the size. Round, rectangular, flat oval, and flexible ducts. Size by friction rate or air velocity. A color-coded performance badge tells you instantly if your duct is optimal, too fast, too slow, or at risk.
ENGINEERING-GRADE ENGINE
Calculations use the Darcy-Weisbach friction equation with Colebrook-White solver — the industry-standard method for duct design. Nine material types with published roughness values: galvanized steel (spiral & rectangular), flexible duct (metallic & non-metallic), fiberglass duct board, fibrous glass liner, PVC, aluminum, and concrete.
FITTINGS & PRESSURE DROP
Calculate total system pressure drop including straight run and all fittings. Ten fitting types with industry-standard loss coefficients: 90° and 45° elbows (round and rectangular), mitered elbow, tee branch and straight-through, concentric reduction, enlargement, and butterfly damper.
PRO MODE
Unlock full 2D lookup tables for rectangular elbows and concentric reductions, plus A/B ratio selector for flat oval ducts. Bilinear interpolation for accurate results at any H/W or area-ratio geometry.
ORGANIZE YOUR WORK
Save calculations with a custom name and notes. Group them into color-coded projects. Export individual calculations as text or PDF, and full projects as CSV. Search your entire history in one tap.
IMPERIAL & METRIC
Switch between I-P and SI units at any time. All inputs and outputs update instantly across every screen.
I-P: CFM · in · ft/min · inWC/100ft
SI: L/s · mm · m/s · Pa/m
6 LANGUAGES
English · Français · Español · Português · Deutsch · Italiano
— 100% offline. No account. No subscription. —
Ratings & Reviews
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- We add iPad support of the app.
- You can now rate the app from the settings.
The developer, High Intent Labs, 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 Linked to You
The following data may be collected but it is not linked to your identity:
- Other Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Sirius Advisory Group Ltd
- Size
- 3.5 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © Sirius Advisory Group Ltd