# Duct Calc Pro — HVAC Duct Sizing Calculator

> HVAC Duct Sizing Calculator (iPhone/iPad app by SHINOBU MIYAHIRA.)

- Source: https://appshunter.io/ios/app/duct-calc-pro/id6789541788 (this page in markdown: same URL + `.md`)
- Developer: [SHINOBU MIYAHIRA](https://appshunter.io/developer/6782739570)
- Category: Productivity
- Price: $5.99
- Age rating: 4+
- Requires: iOS 17.0 · 1 MB
- Languages: American English
- Released: 2026-07-16
- Data updated: 2026-08-16
- User reviews in markdown: https://appshunter.io/ios/app/duct-calc-pro/id6789541788/reviews.md

## What is Duct Calc Pro?

Duct Calc Pro is a complete duct design toolkit for HVAC technicians, installers, and contractors. Seven calculators, a job workspace with PDF reports, and built-in reference tables - all offline, right in your pocket.

CALCULATORS (7)
- Duct Sizing: CFM + friction rate to recommended round duct size (equal friction method)
- Velocity / CFM: check FPM through round or rectangular duct, both directions
- Equivalent Diameter: rectangular to round conversions
- Room CFM: room dimensions x air changes per hour (typical ACH table built in)
- Grille & Register Sizing: required free area and size from CFM and target face velocity
- Static Pressure Budget: worksheet from external static down to available friction rate
- CFM Capacity Table: airflow and velocity for every standard round size at your friction rate

JOBS - YOUR ON-SITE WORKSPACE
Create a job, add rooms (dimensions or direct CFM), and get per-room duct sizes and velocities instantly. Export a clean Job Summary PDF with totals and recommended trunk size - ready to hand to the builder or inspector.

REFERENCE
Typical velocity recommendations, standard duct sizes, friction rate guidance, and ACH tables - always available offline.

- Imperial and Metric units
- Calculation history with one-tap reuse
- No account, no ads, works fully offline

Note: Results are estimates for preliminary sizing. Final design must follow applicable codes and engineering judgment.

## Chart rankings

- #197 in Top Paid · Productivity (US App Store)


## Version history (last 1 release)

### 1.0 — 2026-07-16

No release notes.

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All apps by SHINOBU MIYAHIRA: https://appshunter.io/developer/6782739570

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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 2026-08-16.*