# Ductulator - Duct Sizing — user reviews > 22 indexed App Store user reviews of Ductulator by Wassim Murr, rated 4.70/5 from 317 ratings. - Source: https://appshunter.io/ios/app/ductulator-duct-sizing/id1474939475/reviews - App overview in markdown: https://appshunter.io/ios/app/ductulator-duct-sizing/id1474939475.md - Rating breakdown: 5★ 282 · 4★ 14 · 3★ 7 · 2★ 3 · 1★ 11 ## Newest reviews (2 of 22) ### 3/5 — No Flex in duct calcs *2023-09-25, version 3.1.1* Sadly, $2.99 spend, to discover it’s useless to me, without having the option to select “Flex” in duct calculations ### 4/5 — Very Nice *2023-08-22* Would love to see an option for flex. **Developer response:** It’s coming in the next update! Edit: Latest update is now live! It features ‘Flex’ duct calculations. Thanks for the feedback! ## Most critical reviews (10 lowest-rated) ### 1/5 — Not what I need *2026-08-04, version 3.5* This app should be free, it says duct sizing. It only tells you what velocity and CFM a duct can do. I want my money back. ### 1/5 — Not what I was looking for *2025-08-11, version 3.4* Update- I got your email. I understand the way you have the app set up I just didn’t understand it before I bought the app. The function of your app is pretty much pointless for anything I need it for. If I want to size a traditional residential HVAC duct system this does not help. Your app mostly seems to be used to figure out numbers just for fun. Who cares what the velocity of 500 CFM going through 6 inch flex? You can’t get 500 CFM through 6 inch flex anyway so why would you want to know that number? End Update. You need to be able to pick 6 inch flex and then the app tell you how many CFM can go through that. The way this is set up now is just silly. I like the idea you can get velocity, but you need to know how many CFM goes through all the different sizes. Now I have to buy another app. ### 1/5 — Not what I was looking for *2025-08-08* You need to be able to pick 6 inch flex and then the app tell you how many CFM can go through that. The way this is set up now is just silly. I like the idea you can get velocity, but you need to know how many CFM goes through all the different sizes. Now I have to buy another app. **Developer response:** Hi, thanks for your feedback! The air flow-rate that could go through a given duct size varies depending on the friction rate or velocity you wish to set as limit. Thus, in ‘Ductulator’ mode, you can set a duct size and then check which CFM yields the Friction/Velocity limit you want; this would be the value you’re looking for, just like using the traditional ductulator! Hope this helps. ### 1/5 — WHY WAS I CHARGED ?? *2025-06-01, version 3.4* I downloaded the app for free then was charged recently for $4.26 when I never signed up for a subscription or anything. The app is a scam I guess ? ### 1/5 — Decimal point *2025-04-10, version 3.3.9* Decimal point doesnt work on calculator, dont waste cash on this… ### 1/5 — Ductculator *2024-12-30, version 3.3.5* This new update version is not good they should go back to the original version! ### 2/5 — It’s ok at best *2024-03-07, version 3.3.1* Can’t punch in duct size to see what the cfm is very limited on what you can do save your money but it gives you different duct options if that’s what your trying to do ### 2/5 — Friction rate… *2022-08-26* Friction rate can't be changed in the latest version. ductulator is broken. Please fix this mistake. **Developer response:** Hello, and thank you for your feedback! We tried replicating the issue you are describing, but all the inputs are working correctly. Would you send us some screenshots to welmurr@icloud.com, so we could look into them? ### 3/5 — Pretty useful *2024-09-18, version 3.3.5* Comes in handy but limits what sizes you can pick. Not sure if it’s a bug but I wanted to see what my friction rate was for 16x25 and I can get the 16 but it skips from 24-26 and that happens often. ### 3/5 — Needs work *2023-10-27, version 3.3* The new flex option isn’t working properly. ## Most praised reviews (10 highest-rated) ### 5/5 — BEST D**N APP OUT THERE *2026-07-27, version 3.5* You couldn’t find a better app for adjusting duct sizes and just overall use ### 5/5 — Duct guy *2026-07-10, version 3.5* Very helpful ### 5/5 — Duct Design *2025-03-25, version 3.3.8* An excellent tool to have for duct design. Seamlessly transitions between imperial and metric values when duct sizes are metric with imperial airflow quantities. Saved me a lot of time and the app is very easy to use. ### 5/5 — Best duculator for IPhone *2025-02-05, version 3.3.8* Very easy to use in the field. I use it everyday when measuring out duct runs !! ### 5/5 — Review *2025-02-03* Very good duct sizer and easy to use ### 5/5 — Don't be afraid to invest in this very useful tool. *2023-12-27, version 3.3.1* Excellent application. Don't be afraid to invest in this very useful tool. The application perfectly meets its objective. I recommend it 100% ### 5/5 — Options *2023-04-07, version 2.2.2* I love the App. It’s easy to use I just wish there were more options like selecting round or square duct as opposed to just only using Cfm. ### 5/5 — It’s a must have *2021-08-06, version 2.2.1* I get to retire my 25 year old Ductulator ### 4/5 — Solid app, not quite 5/5 *2025-04-15, version 3.4* The only thing holding the app back IMO is the omission of flat oval ducts. They’re uncommon, but it’s the only thing the app can’t do that has caused me to have to reach for the less convenient methods. ### 4/5 — Let me reverse lookup *2023-10-26, version 3.3* Love that it gives you different options for sizing but I wish I could enter a duct size and get a cfm value from it. --- *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 2026-09-02.*