# Air Duct Size Calculator — Pressure Drop & Friction Rate

> Pressure Drop & Friction Rate (iPhone/iPad app by Alona Nesterenko.)

- Source: https://appshunter.io/ios/app/air-duct-size-calculator/id6761648095 (this page in markdown: same URL + `.md`)
- Developer: [Alona Nesterenko](https://appshunter.io/developer/1890650834)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 18.0 · 3 MB
- Languages: American English
- Released: 2026-04-07
- Data updated: 2026-08-26
- User reviews in markdown: https://appshunter.io/ios/app/air-duct-size-calculator/id6761648095/reviews.md

## What is Air Duct Size Calculator?

Air Duct Size Calculator is a focused HVAC tool for professionals who need fast duct sizing, airflow checks, and clear pressure-related calculations. It is built for practical work: direct input, clear results, and quick access to the engineering values behind each calculation.

Use it to size round and rectangular ducts from airflow with either a target velocity or a target friction rate. You can review exact results, compare practical rounded sizes, and work through realistic options without relying only on a traditional ductulator workflow. The app also lets you analyze an existing duct, solve section pressure-drop relationships, estimate run loss, and compare round and rectangular conversions in one place.

Key capabilities:

• Size round and rectangular ducts by velocity or friction  
• Analyze an existing duct from airflow, velocity, or friction  
• Solve pressure-drop relationships for total pressure drop, friction rate, straight length, or added equivalent length  
• Estimate run loss using straight length, equivalent length, fitting loss coefficient K, and allowable-loss checks  
• Convert round to rectangular and rectangular to round  
• View equal-area references alongside equivalent conversions  

Built for practical HVAC work:

• Imperial and metric defaults  
• Airflow units including CFM, CFS, m³/s, L/s, and m³/h  
• Velocity, dimension, length, temperature, friction, and pressure unit controls  
• Fractional inch support for dimensions  
• Material presets, including flexible duct options with correction support  
• Local settings persistence on device  

When you need more than a quick answer, engineering detail stays visible. The app can show Reynolds number, Darcy friction factor, dynamic pressure, hydraulic diameter, equivalent round diameter, air density, and dynamic viscosity, so you can see the values behind the result instead of treating it like a black box.

Engineering details include:

• Reynolds number  
• Darcy friction factor  
• Dynamic pressure  
• Hydraulic diameter  
• Equivalent round diameter  
• Air density  
• Dynamic viscosity  

Air Duct Size Calculator is intentionally focused on duct sizing, duct analysis, pressure-drop workflow, and equivalent conversion. It is not presented as a full network design suite, report export tool, fitting database, or cloud project system.

If you need a practical duct calculator with transparent assumptions and a clean workflow, Air Duct Size Calculator is built for that job.

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Lifetime Access | $1.99 | one-time |



## Version history (last 2 releases)

### 1.1 — 2026-05-02

UI Improvements

### 1.0 — 2026-04-07

No release notes.

## Apps similar to Air Duct Size Calculator

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [DuctSizer Pro](https://appshunter.io/ios/app/ductsizer-pro/id6772545249) | 5.0 (2) | Free | Utilities |
| [Duct Sizer Calc HVAC](https://appshunter.io/ios/app/duct-sizer-calc-hvac/id6764646921) | — | $0.99 | Utilities |
| [ChekDuct](https://appshunter.io/ios/app/chekduct/id6768763588) | — | Free | Utilities |
| [Plumbing Calculator & Tools](https://appshunter.io/ios/app/plumbing-calculator-and-tools/id6762154217) | — | Free | Utilities |
| [DuctPro](https://appshunter.io/ios/app/ductpro/id6771761655) | — | Free | Utilities |
| [Duct Calculator - DuctCalc](https://appshunter.io/ios/app/duct-calculator-ductcalc/id6757307937) | 4.6 (32) | Free | Utilities |

## More apps by Alona Nesterenko

- [Pips & Lot Size Calculator](https://appshunter.io/ios/app/pips-and-lot-size-calculator/id6751819770)
- [ADR Tracker](https://appshunter.io/ios/app/adr-tracker/id6752336382)
- [Forex TP & Risk Calculator](https://appshunter.io/ios/app/forex-tp-and-risk-calculator/id6752648514)
- [Nail Health Scanner](https://appshunter.io/ios/app/nail-health-scanner/id6752996793)
- [Tooth Shade Scanner](https://appshunter.io/ios/app/tooth-shade-scanner/id6753220158)
- [Chart Scanner](https://appshunter.io/ios/app/chart-scanner/id6753593137)

All apps by Alona Nesterenko: https://appshunter.io/developer/1890650834

## Related topics

[air duct size calculator](https://appshunter.io/ios/topics/air-duct-size-calculator) · [air duct calculator](https://appshunter.io/ios/topics/air-duct-calculator)

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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 2026-08-26.*