# DuctCalc.Ca — Ductulator Duct Calculator

> HVAC duct sizing calculator for round and rectangular ducts. (iPhone/iPad app by Firas Kneifati.)

- Source: https://appshunter.io/ios/app/ductcalcca/id1434460375 (this page in markdown: same URL + `.md`)
- Developer: [Firas Kneifati](https://appshunter.io/developer/1434460374)
- Category: Utilities, Productivity
- Price: Free with in-app purchases
- Rating: 1.90/5 from 20 App Store ratings · 14 written reviews indexed
- Age rating: 4+
- Requires: iOS 11.3 · 9 MB
- Languages: English
- Released: 2019-03-17
- Data updated: 2026-06-10
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/ductcalcca/id1434460375/reviews.md

## What is DuctCalc.Ca?

DuctCalc.Ca is the iOS offline version of the most popular online ductulator app (ductcalc.ca)
Enjoy using the app with no internet connection when subscribed!

App engineering explanation:
------------------------------
Equal Friction Method: 
Using a predefined static pressure loss per unit of duct length, DuctCalc.Ca Ductulator App calculates the diameter of round duct and the other dimension of rectangular duct. Based on the calculated dimensions, the air velocity will be calculated for both duct shapes and dimensions. 

Velocity Method: 
Using a predefined air velocity, DuctCalc.Ca Ductulator App calculates the diameter of round duct and the other dimension of a rectangular duct. Based on the calculated dimensions, the static pressure loss will be calculated for both duct shapes and dimensions. Note that unlike conventional ductulators, this ductulator will calculate the dimensions of the rectangular duct based on the given velocity and it then calculates the static pressure loss for the rectangular duct based on the given velocity and dimensions. Most old calculators will only use the given velocity to calculate the diameter of the round duct then it calculates the static pressure loss for the round duct and uses that static pressure to calculate the rectangular duct dimensions which is not the case here for more precise velocity output. 

Colebrook equation is used to solve for Darcy's friction factor and calculates the static pressure loss in the duct until it matches the desired input at defined airflow and absolute roughness of the inner material of the duct touching the moving air.

In-App Purchases:
-------------------
• With no subscription the app will calculate for an air flow range between (950 and 1100 [cfm]).
To activate full air flow functionality. There are four subscription options: one month, three months, six months and one year.
• All subscription options will activate the "Full Air Flow Functionality" of the duct sizing app for that specific subscription period. The full air flow range is (1 to 500,000 [CFM] or 1 to 235,974 [L/s] in metric units).
• Payment will be charged to iTunes Account at confirmation of purchase.
• Any unused portion of a free trial period, if offered, will be forfeited when the user purchases a subscription to that publication, where applicable.

Privacy Policy: https://ductcalc.ca/?page=agreement
Terms of Service: https://ductcalc.ca/?page=agreement

## Key features

- Duct sizing calculator
- Equal Friction Method
- Velocity Method
- Round and rectangular duct support
- Offline functionality
- Full air flow range activation

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| One Month Full Air Flow | $6.99 | one-time |
| Three Months Full Air Flow | $17.99 | one-time |
| Six Months Full Air Flow | $29.99 | one-time |
| One Year Full Air Flow | $49.99 | one-time |


## Recent user reviews (10 of 14)

All indexed reviews: https://appshunter.io/ios/app/ductcalcca/id1434460375/reviews.md

### 1/5 — Useless

*2024-08-28*

Useless app and a more useless website

### 1/5 — Subscription

*2023-05-24*

You have to pay to use the app.

**Developer response:** Yes you have to pay and we don’t need cheap users like you

### 5/5 — Nice Graphical Interface

*2022-02-26*

I like how it draws both duct shapes and shows the relative dimensions graphically in addition to showing the numbers. There is a little charge for using app, but it's the case for any quality app.

### 5/5 — Worth the money

*2022-01-21*

The most user friendly app for duct design.
It’s very easy to switch between friction and velocity methods and compare both rectangular and round duct dimensions.
I’m surprised that there are some reviews here complaining about the little subscription payment they have to pay which is less than the cost of a cup of coffee a week.
It’s definitely worth every penny! Strongly recommended

**Developer response:** Thanks for being fair Igor!

### 5/5 — Eng. Fadi Saflo

*2021-12-27, version 1.2*

User friendly and practical

### 5/5 — Very useful

*2021-12-26*

The best app I have ever used. Very useful.

### 5/5 — Great App. Highly recommended

*2021-12-26, version 1.2*

I think this is a great app and it is worth every penny.

### 1/5 — Paid app

*2021-10-07*

Can’t do anything until you pay

**Developer response:** Which is normal for any engineering tool. It can still be tested without payment with a limited airflow range though.

### 1/5 — Unusable without payment

*2020-03-19*

You have to pay for a subscription to use it unless your airflow always hovers around 1000cfm. Just use the website. It’s free and great.

**Developer response:** The paid version is what is funding the free great website. This kind of reviews may deprive everyone of the free stuff you like when no one is ready to pay!

### 1/5 — What a joke

*2020-02-13*

You can’t use the free app unless the airflow is within 950-1100 cfm

**Developer response:** It is your problem if you don’t like paying for engineering tools! What a shame!

## Frequently asked questions about DuctCalc.Ca

### What is DuctCalc.Ca?

DuctCalc.Ca is an iOS app that functions as a ductulator, calculating duct dimensions and air velocity. It offers two primary calculation methods: Equal Friction and Velocity, supporting both round and rectangular duct types.

### How does DuctCalc.Ca calculate duct dimensions?

It uses the Equal Friction Method, which calculates duct diameter or rectangular dimensions based on a predefined static pressure loss per unit length. Alternatively, the Velocity Method calculates dimensions using a predefined air velocity, then determines the static pressure loss.

### What are the limitations of the free version of DuctCalc.Ca?

Without a subscription, DuctCalc.Ca calculates for an air flow range between 950 and 1100 CFM. To access the full air flow functionality, a subscription is required.

### What subscription options are available for DuctCalc.Ca?

DuctCalc.Ca offers four subscription options: one month, three months, six months, and one year. All subscriptions activate the 'Full Air Flow Functionality' for their respective durations.

### Does DuctCalc.Ca require an internet connection?

The app is designed as an offline version of its online counterpart, meaning it can be used without an internet connection once subscribed. This allows for convenient use in various work environments.

### What is the user rating for DuctCalc.Ca?

DuctCalc.Ca has a user rating of 1.9 stars from 20 ratings. This suggests that while the app offers useful functionality, there may be areas for improvement based on user feedback.

### Is DuctCalc.Ca suitable for all ages?

DuctCalc.Ca has an age rating of 4+. This indicates it is generally considered appropriate for a wide range of users, though its primary utility is for professionals.

### How often is DuctCalc.Ca updated?

The latest version of DuctCalc.Ca is 1.2, which was last updated on November 19, 2019. This indicates a relatively infrequent update schedule.

## Version history (last 3 releases)

### 1.2 — 2019-11-19

User interface improvement.
Integration with ductcalc.ca/premium subscriptions.

### 1.1 — 2019-03-19

User interface improvements and iPad compatibility.

### 1.0 — 2019-03-15

No release notes.

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## More apps by Firas Kneifati

- [FormalChat](https://appshunter.io/ios/app/formalchat/id6759956520)

All apps by Firas Kneifati: https://appshunter.io/developer/1434460374

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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 2026-06-10.*