# HVAC Duct Flow: Duct Sizing — Size ducts with confidence

> Size ducts with confidence (iPhone/iPad app by Ahmet Selvi.)

- Source: https://appshunter.io/ios/app/hvac-duct-flow-duct-sizing/id6819098420 (this page in markdown: same URL + `.md`)
- Developer: [Ahmet Selvi](https://appshunter.io/developer/1864624578)
- Category: Utilities, Productivity
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 6 MB
- Languages: American English, Arabic, French (France), German (Germany), Indonesian, Italian, Japanese, Korean, Polish, Brazilian Portuguese and 5 more
- Released: 2026-10-17
- Data updated: 2026-10-24

## What is HVAC Duct Flow?

Get fast answers for everyday duct and grille sizing checks. Size rectangular and round ducts, grilles and diffusers in one practical tool for the office or the field.

• Size rectangular and round (spiral) ducts by constant velocity or equal friction.
• Check velocity, friction loss (Pa/m) and velocity pressure for any duct size.
• Convert a rectangular a×b duct to its equivalent round diameter, and back.
• Size 8 grille and diffuser types with velocity, pressure drop and throw.
• Share one-page PDF reports and switch between SI and IP units.
• Use the app offline on iPhone and iPad, in 15 languages.

Turn the airflow dial or type an exact value, choose a method, and review the results as they update live. Duct material roughness, air temperature and altitude are taken into account, and velocity warnings follow residential, office and industrial limits that you can tighten in Settings.

Designed for mechanical engineers, HVAC professionals and technical teams working in design, estimating or on site. Calculations follow ASHRAE Fundamentals (Darcy–Weisbach with the Colebrook equation). The app is completely free, with no ads and no data collection.

Download HVAC Duct Flow and make your next duct calculation easier.

Results are for guidance; the responsibility for design and installation remains with the engineer.

## Is HVAC Duct Flow safe?

Not enough ratings yet to assess HVAC Duct Flow.

## Is HVAC Duct Flow legit?

HVAC Duct Flow: Duct Sizing appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for HVAC Duct Flow is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 3 releases)

### 1.2 — 2026-10-23

In this version:
• + / − buttons on the airflow card: after turning the dial, step the airflow to the next round value with one tap (hold to repeat). Also works for the round duct diameter.
• Stability: fixes a crash on iPad that could close the app while using the velocity warning card.

### 1.1 — 2026-10-19

In this version:
• Airflow helpers: in the airflow keypad, calculate the airflow from air changes (area × height × changes per hour) or outdoor air per person (typical values by space type).
• US sizes: choosing imperial units switches duct sizes to the SMACNA inch standard.
• Better recommendation: the recommended rectangular size is now the one with the least sheet metal among all suitable sizes; standard sizes up to 2000 mm are scanned.
• New target velocity and friction card: value on the left, − / + on the right; it no longer changes by accident while you scroll.
• Precision fixes for inch, CFM and l/s input, plus Arabic report and layout improvements.
• The in-duct airflow animation is gone for a cleaner screen.

### 1.0 — 2026-10-17

No release notes.

## More apps by Ahmet Selvi

- [Şantiye Takip-Mekanik Tesisat](https://appshunter.io/ios/app/santiye-takip-mekanik-tesisat/id6757112307)
- [SprinkCalc: Fire Sprinkler](https://appshunter.io/ios/app/sprinkcalc-fire-sprinkler/id6757990855)
- [MEP Calc: HVAC Fire Calculator](https://appshunter.io/ios/app/mep-calc-hvac-fire-calculator/id6759204237)
- [TS EN 12845 Sprinkler & BYKHY](https://appshunter.io/ios/app/ts-en-12845-sprinkler-and-bykhy/id6793219167)

All apps by Ahmet Selvi: https://appshunter.io/developer/1864624578

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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 2026-10-24.*