# HVAC Duct Sizer — user reviews > 39 indexed App Store user reviews of HVAC Duct Sizer by Carmel Software Corporation, rated 2.90/5 from 8 ratings. - Source: https://appshunter.io/ios/app/hvac-duct-sizer/id317970395/reviews - App overview in markdown: https://appshunter.io/ios/app/hvac-duct-sizer/id317970395.md - Rating breakdown: 5★ 3 · 4★ 0 · 3★ 1 · 2★ 1 · 1★ 3 ## Newest reviews (11 of 39) ### 4/5 — high quality accuracy. *2014-07-15* Very accurate and useful. Relatively easy to use if you know how to properly size ducts. The only problem with the app is after you enter a value, the screen stops scrolling up and down so you can't see the results. You have to back out to the main menu then re-select the category (i.e. Size by airflow) to see the answer. ### 4/5 — Swigs *2012-07-07, version 1.7* It's ok ### 4/5 — Wawa *2012-04-28, version 1.7* Good app ### 4/5 — Works great. *2012-01-07* You should see the eyes of an engineer when I pull out my phone and use this app to show him that I can change the size of his duct correctly because of a beam the engineer "missed" when designing the system. The best is when I go into a home and show the owners why my competitor installed too small of ductwork for their top of the line a/c unit. ### 4/5 — Nice and handy! *2011-01-23, version 1.7* Just learning to properly size ducts using Manual D, only complaint is the list of materials doesn't include fiberglass duct board ### 5/5 — Great application *2011-01-08, version 1.7* I am making decisions always, with this application I can double check the work of our contractors fast and easy. ### 5/5 — Great update *2010-07-12* I find I use this daily for doing rule-of-thumb duct calcs. Results appear accurate and it's good to see periodic updates coming out. I'd love to see a native iPad version developed, too. ### 4/5 — Happy so far, but..... *2010-07-09* My only complaint is that there is no rectangular to round duct conversion function. This would be extremely helpful to me. Other than that I am pleased with the app. ### 5/5 — Works great on my old iPod touch *2010-04-25* I downloaded it on my old iPod touch (2 years old, I think). Anyway, it works great. I find that this app are a godsend; it is convenient to use, so that I do not have to run to the nearest computer every time I need to estimate duct sizes or velocity flow. Keep them coming! ### 5/5 — HVAC Design & Sales *2010-03-04* This is the most useful app I have on my phone, as my profession is designing HVAC systems. The app is intuitive, versatile and functional. It fits in my pocket. It's accurate. I use it every day. ### 3/5 — No aspect ratio conversion *2010-01-07* Does not convert square to round or vise versa. Miss leading app. Very informative for the scientific need but no pratical use for me. Waste of £3.99 ;<<< ## Most critical reviews (10 lowest-rated) ### 1/5 — ความคุ้มค่า *2025-08-15, version 6.95* ลองใช้แล้วไม่คุ้มเงิน ตั้งค่าอะไรไม่ได้เลย ยิ่งใช้งานยิ่งงง ### 1/5 — Worked before update *2014-02-21, version 2.0* Was a great app but now doesn't show top of screen after entering values. Sliders are impossible to set accurately too. They always move when your finger is lifted. ### 1/5 — Don't Waste Your Money *2013-01-02, version 1.8* You can get the same program by downloading the Johnstone Supply app for free. ### 1/5 — Free elsewhere *2012-01-30, version 1.7* You can find this same exact app for free with the Johnstone supply app. So save your $6.99 ### 1/5 — Piece of crap *2011-07-15, version 1.7* Nothing more than a slide rule. I want My money back!!!!!!! ### 1/5 — Keep looking *2011-03-24, version 1.7* Very user unfriendly. I hate it. ### 1/5 — It is a simple toys , not professional *2011-02-02, version 1.7* Not a good value,if you try cook you will see a big difference ### 1/5 — Not worth the money *2010-10-06, version 0* Not good ### 1/5 — Big Bugs *2009-12-23, version 0* If you set the max limit and increment for data in the duct inputs window and you come back in the user input windows, the rules bars indicate different limits. I'm not able to reset the limits values and the conclusion!!! I can not use this tool. I'm comfused !! ### 1/5 — iPod needed *2009-10-31* Unfortunately I bought this app and then found out it does not work on the iPod, what's the point if it can't work on both.....should have been written to work on iPod touch as well what a shame. ## Most praised reviews (10 highest-rated) ### 5/5 — Great duct sizer *2020-03-07* I’m an HVAC engineer and I use this at work almost every day. It’s a great way to quickly size a run of duct and easily switch between duct types. ### 5/5 — A classic *2014-08-13* I’ve had this app for 4 or 5 years now, and I can’t believe how use it still is. It’s great that Carmel keeps updating it and now I can use it on my iPad. ### 5/5 — Mechanical Contractor *2012-11-15* Use this app professionally, easy to use, always on target! ### 5/5 — Poor quality app *2012-11-15, version 1.8* Not worth the money. ### 5/5 — Excellent *2012-11-02* This app is excellent tool for HVAC tech. Thanks for help us. ### 5/5 — A classic *2012-09-28* This app has been around for years, and I finally got around to rating it. I use it daily and it's all i can ask for a simple duct sizing app. I love the emailing capability. Sure beats a ductulator. Love it! ### 5/5 — Very nice! *2012-01-22* This app is very good. Wish I had it when I did A/C service work. Electronic ductilator ++ ### 5/5 — Awesome app *2011-04-28, version 1.7* Awesome ### 5/5 — Best Ductulator You Can Get!!! *2011-02-20, version 1.7* This is hands down the best ductulator you can get. The variety of options allow you to tweak whatever design conditions you would like. Waiting for a just now recommended upgrade for a total friction loss option where you could put together an entire system in order to size a blower. ### 5/5 — Great *2011-01-19, version 1.7* Finally an app I don't regret buying --- *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 2026-08-14.*