# DuctSizer: Duct Calculator — HVAC sizing: friction & CFM

> HVAC sizing: friction & CFM (iPhone/iPad app by Alican Basak.)

- Source: https://appshunter.io/ios/app/ductsizer-duct-calculator/id6788267429 (this page in markdown: same URL + `.md`)
- Developer: [Alican Basak](https://appshunter.io/developer/1871159079)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 17.0 · 7 MB
- Languages: American English
- Released: 2026-07-16
- Data updated: 2026-08-02
- User reviews in markdown: https://appshunter.io/ios/app/ductsizer-duct-calculator/id6788267429/reviews.md

## What is DuctSizer?

Size ducts in seconds — right from the ladder.

DuctSizer turns airflow into duct sizes instantly. Enter CFM (or L/s) and a friction rate or velocity target, and read every valid size at a glance: round diameter plus rectangular options for the joist depth you actually have.

SIZING, FREE
• Round and rectangular results, live as you type
• Friction and velocity for every option, with clear limit warnings
• Imperial and SI units (CFM, L/s, m³/h · in.wg/100 ft, Pa/m)
• Material roughness shown for galvanized, spiral, duct board, and flex

DUCTSIZER PRO — ONE-TIME PURCHASE
• Reverse mode: pick a size, get its max airflow — including flex with honest compression derating, and flat-oval ducts
• Fittings & pressure loss: total effective length and Manual D friction rate (FR = ASP × 100 / TEL)
• Altitude and temperature density correction, always visible
• Saved jobs: group runs by project and export CSV or PDF

THE MATH, DONE RIGHT
Calculations follow the ASHRAE friction chart with Darcy–Weisbach and Haaland for material roughness, and Huebscher equivalents for rectangular and flat-oval ducts. Results match the cardboard wheel you trained on — with the steps the wheel can't do.

BUILT FOR THE FIELD
• Works 100% offline — no account, no sign-in
• No analytics or tracking; your data stays on your device
• Dark, glare-friendly interface with big touch targets
• iPhone and iPad, iOS 17 or later

Pro is a single one-time purchase. No subscription, ever.

DuctSizer is an independent app and is not affiliated with or endorsed by ASHRAE, ACCA, or Trane.


Privacy Policy: https://ductsizer.app/privacy
Terms of Use: https://ductsizer.app/terms

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| DuctSizer Pro | $9.99 | one-time |



## Version history (last 2 releases)

### 1.0.2 — 2026-07-28

Rebuilt on native iOS controls.

• New Home Screen widget shows the last duct size you worked out
• “Size a duct” now works from Shortcuts, Spotlight and Siri
• Every screen moved to the system tab bar, lists and pickers
• Numeric keyboards now have a Done button
• Full Dynamic Type support — numbers scale with your text size
• Fixed decimal separators on non-US region formats

### 1.0.0 — 2026-07-16

No release notes.

## More apps by Alican Basak

- [Quippy: Conversation Cards](https://appshunter.io/ios/app/quippy-conversation-cards/id6763020627)
- [Mantria: Vent & Name Feelings](https://appshunter.io/ios/app/mantria-vent-and-name-feelings/id6767613730)
- [Notabe: AI Notes & Voice Memo](https://appshunter.io/ios/app/notabe-ai-notes-and-voice-memo/id6768305809)
- [Humanizer: AI Text Rewriter](https://appshunter.io/ios/app/humanizer-ai-text-rewriter/id6770480013)
- [Life in the UK Test Pass Prep](https://appshunter.io/ios/app/life-in-the-uk-test-pass-prep/id6776806223)
- [My Australian Citizenship Test](https://appshunter.io/ios/app/my-australian-citizenship-test/id6776807571)

All apps by Alican Basak: https://appshunter.io/developer/1871159079

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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 2026-08-02.*