# HVAC Duct Sizer Pro — Offline Duct Size Calculator

> Offline Duct Size Calculator (iPhone/iPad app by Duong Nguyen Huu.)

- Source: https://appshunter.io/ios/app/hvac-duct-sizer-pro/id6792515177 (this page in markdown: same URL + `.md`)
- Developer: [Duong Nguyen Huu](https://appshunter.io/developer/1887479789)
- Category: Utilities, Business
- Price: $0.99 (on sale, was $1.99)
- Age rating: 4+
- Requires: iOS 16.4 · 30 MB
- Languages: American English
- Released: 2026-07-29
- Data updated: 2026-08-08
- User reviews in markdown: https://appshunter.io/ios/app/hvac-duct-sizer-pro/id6792515177/reviews.md

## What is HVAC Duct Sizer Pro?

HVAC Duct Sizer Pro is the digital Ductulator built for HVAC engineers and contractors who need accurate duct sizing on the spot — no signal required, no subscription, no clutter.

Every calculation runs instantly on your device, based on the same ASHRAE Fundamentals formulas used in professional duct design: Colebrook-White friction factor, Darcy-Weisbach pressure loss, and the Huebscher rectangular-equivalent method.

SIZE A DUCT
Enter your airflow plus a target friction rate or velocity, and get:
• Recommended round duct diameter — exact and nearest standard size
• Rectangular equivalent (equal-friction, Huebscher method)
• Resulting velocity, friction rate, and Reynolds number

ANALYZE AN EXISTING DUCT
Already have a duct in place? Enter the airflow and its dimensions (round or rectangular) to instantly get velocity, friction rate, velocity pressure, and Reynolds number.

BUILT FOR THE FIELD
• 100% offline — works anywhere, with zero setup
• SI and Imperial units, switchable anytime, with independent airflow unit (L/s, m³/h, CFM)
• Five duct material roughness presets, from smooth PVC to fully-extended flex
• Standard or custom air density
• Numeric keypad or system keyboard input, with live recalculation on every keystroke
• Available in English, 日本語, 简体中文, 한국어, Français, Deutsch, Español, and Tiếng Việt

NO SUBSCRIPTIONS. NO ADS. NO ACCOUNT.
HVAC Duct Sizer Pro is a one-time purchase. Buy it once, use it forever — on every job, offline.


From the makers of AirCalc Pro, the psychrometric calculator trusted by HVAC professionals.


## Version history (last 1 release)

### 1.0 — 2026-07-30

No release notes.

## More apps by Duong Nguyen Huu

- [Tích Sản: Giá Vàng & Tài Sản](https://appshunter.io/ios/app/tich-san-gia-vang-and-tai-san/id6761044270)
- [PDFScan Go](https://appshunter.io/ios/app/pdfscan-go/id6761462436)
- [AirCalc Psychrometric](https://appshunter.io/ios/app/aircalc-psychrometric/id6762062746)
- [Daily Health Reminder App](https://appshunter.io/ios/app/daily-health-reminder-app/id6762444133)
- [Meno Health Tracker](https://appshunter.io/ios/app/meno-health-tracker/id6762710155)
- [Barber Việt Nam](https://appshunter.io/ios/app/barber-viet-nam/id6763964976)

All apps by Duong Nguyen Huu: https://appshunter.io/developer/1887479789

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-08.*