Comparison

HVAC Duct Sizer vs Dr. DE

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

HVAC Duct Sizer

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
Read full description

The HVAC Duct Sizer app is the #1 selling duct sizing application for the Apple iPhone and iPad. Tens of thousands of happy users have downloaded this useful application for performing quick and simple duct sizing analysis. The HVAC Duct Sizer is a universal duct sizing app so that it works on both the iPhone and iPad and adjusts its screen size accordingly. Just a couple of comments from our users: "I'll be presenting your iPhone program to my HVAC class as an easy compact tool to have in hand when making sales and service calls." - R. Black "I like this app and use it daily" - V. Joe The Duct Sizer application allows you to quickly size one HVAC duct run or a range of duct sizes using the constant friction method. Think of this application as a digital version of the classic Trane Ductulator. In the "Size by Airflow" mode, you can specify the total airflow in CFM (or L/s), the aspect ratio and one of either the velocity of air or the friction loss per 100 feet (30 meters). The results include both the exact and rounded height and width (or diameter) dimensions and the calculated velocity and friction loss. In the "Size by Dimensions" mode, you can analyze an existing duct system. There are options to input the existing duct dimensions and one of either the airflow or velocity values to derive the calculated duct friction loss. In the "Range of Duct Sizes" mode, you can specify minimum and maximum friction loss and airflow values to display a range of duct sizes that fall in between the friction loss bounds. You can specify additional parameters such as the duct shape (rectangular, round, or oval), the air temperature and the air pressure. You can also choose to display values in either English (IP) or Metric (SI) units. This application uses slider controls that allow you to quickly increment or decrement the input values and immediately observe the calculated results. Finally, you can email all of the inputs and results from all 3 input modes to perform further analysis using your desktop computer. The email includes a PDF report, HTML text and a .CSV attachment that can be imported into any popular spreadsheet. The "HVAC Duct Sizer" application was designed by Carmel Software Corporation, a leader in HVAC design software since 1995. In fact, Autodesk (the makers of AutoCAD) acquired our load calculation software and incorporated it into their leading 3D modeling software called Revit. In addition, we developed a number of customized apps for ASHRAE, DNV GL, and other organizations. We also offer the following additional apps for the iPhone and iPad: 1. HVAC Residential Load Calcs for iPhone and iPad 2. HVAC Quick Load Plus 3. HVAC Quick Load 4. HVAC Toolkit 5. HVAC Pipe Sizer – Gas Low Pressure 6. HVAC Pipe Sizer - Gas High Pressure 7. HVAC Pipe Sizer – Liquid 8. HVAC Pipe Sizer – Steam 9. Steam Tables 10. Psychrometric Plus 11. Psychrometric LT 12. HVAC Pipe Sizer Plus 13. HVAC Pipe Sizer Gas Plus 14. HVAC Toolkit Ultimate 15. HVAC Equipment Locator 16. HVAC ResLoad-J 17. HVAC Psych HD

About

Dr. DE

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
Read full description

Do you want to solve drilling engineering problems in seconds? It is easier than ever before to use Dr. DE Lite mobile app, a must-have toolbox app that includes a substantial collection of functions for every drilling engineer and technician. Bid farewell to flipping through handbooks, textbooks, standards, etc. for answers. This free app, sophisticated yet simple to use, not only saves time and money, but also makes your engineering and sales efforts more reliable and professional. The Dr. DE Lite app is equipped with 29 functions that are divided into 11 groups. --Bit Hydraulics --Casing Centralizer --Hole Cleaning --Hydraulics --Mud Additives --Pipe --Pump --Tank Capacity --Volume and Capacity --Well Control --Unit Conversion

Screenshots

HVAC Duct Sizer4 screens
Dr. DE4 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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

Scorecard5 real differences · 5 level
HVAC Duct Sizer versus Dr. DE: the parameters behind the verdict, then further details
ParameterHVAC Duct SizerDr. DE
Price$4.99Free — better
Rating3.1 (9 ratings)4.5 (15 ratings) — better
Positive reviews62.5% of reviews — better55.6% of reviews
Number of ratings915 — better
Update frequencyEvery 3 monthsEvery 3 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS17.015.6 — better
Further details — not scored
Size1 MB33 MB
Age rating+417+
DeveloperCarmel Software CorporationPegasus Vertex, Inc.

Customer experience

HVAC Duct Sizer

All ratings9 ratings
Positive44.4%
Neutral11.1%
Negative44.4%
Written reviews40 reviews
Positive62.5%
Neutral5.0%
Negative32.5%

Dr. DE

All ratings16 ratings
Positive87.5%
Neutral0.0%
Negative12.5%
Written reviews9 reviews
Positive55.6%
Neutral0.0%
Negative44.4%

In-app purchases

1 purchases

HVAC Duct Sizer

One-time1
  • HVAC Equipment Locator$9.99
None

Dr. DE

No in-app purchases

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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