# HVAC Duct Sizer vs Dr. DE

The clearest difference is price: Dr. DE at Free against HVAC Duct Sizer's $4.99. Dr. DE also leads on rating (4.5 vs 3.1) and in-app purchases (none vs 1). On review sentiment, ratings volume, update cadence and ads there is nothing between them.

Dr. DE is free to download; HVAC Duct Sizer costs $4.99 up front. HVAC Duct Sizer sells 1 one-off in-app purchase. Dr. DE asks for nothing beyond the download.

Dr. DE holds the better App Store score, 4.5 against 3.1. Both are backed by a comparable volume of ratings — 9 and 15 respectively. Written reviews complicate that: 63% of HVAC Duct Sizer's written reviews are positive against 56% of Dr. DE's, so the app with the better star average is not the one people write more warmly about.

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on October 29, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | HVAC Duct Sizer | Dr. DE |
| --- | --- | --- |
| Price | $4.99 | **Free** |
| Rating | [3.1 (9 ratings)](https://appshunter.io/ios/app/hvac-duct-sizer/id317970395/reviews) | **[4.5 (15 ratings)](https://appshunter.io/ios/app/dr-de/id954796004/reviews)** |
| Number of ratings | 9 | **15** |
| Positive reviews | **62.5% of reviews** | 55.6% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | Free with in-app purchases | **Free** |
| Size | 1 MB | 33 MB |
| Requires iOS | 17.0 | **15.6** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | +4 | 17+ |
| Developer | [Carmel Software Corporation](https://appshunter.io/developer/317970398) | [Pegasus Vertex, Inc.](https://appshunter.io/developer/954796003) |

## What reviewers say

### HVAC Duct Sizer

[App page](https://appshunter.io/ios/app/hvac-duct-sizer/id317970395)

This app provides quick and simple HVAC duct sizing analysis. It allows users to calculate duct dimensions based on airflow or existing dimensions, and can also determine a range of duct sizes. Results can be emailed for further analysis.

**Highlights:** Duct sizing by airflow, Duct sizing by dimensions, Range of duct sizes calculation, Rectangular, round, and oval duct shapes, English and Metric unit options, Email results with CSV attachment, HVAC Equipment Locator

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| HVAC Equipment Locator | $9.99 | one-time |


### Dr. DE

[App page](https://appshunter.io/ios/app/dr-de/id954796004)

This mobile toolbox simplifies complex drilling engineering calculations. It offers a comprehensive suite of 29 functions across 11 categories, eliminating the need for handbooks and improving efficiency for engineers and technicians.

**Highlights:** 29 drilling engineering functions, 11 functional groups, Bit hydraulics calculations, Hole cleaning analysis, Well control solutions, Unit conversion tools, Tank capacity calculations

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is HVAC Duct Sizer free?

HVAC Duct Sizer costs $4.99, and also offers in-app purchases.

### Is Dr. DE free?

Dr. DE is free to download, with no in-app purchases.

### Which has better reviews, HVAC Duct Sizer or Dr. DE?

Dr. DE is rated higher. HVAC Duct Sizer averages 3.1 out of 5 from 9 ratings, while Dr. DE averages 4.5 from 15 ratings.

### Do HVAC Duct Sizer or Dr. DE have ads?

Neither HVAC Duct Sizer nor Dr. DE shows ads.

### Which is updated more often, HVAC Duct Sizer or Dr. DE?

HVAC Duct Sizer ships an update every 3 months, and Dr. DE every 3 months. Most recently, HVAC Duct Sizer was updated on October 29, 2026 and Dr. DE on October 24, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*