Duct Calculator vs Quietflex Ductulator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Duct Calculator
This app allows HVAC professionals to quickly and accurately size new ducts or calculate the performance of existing ones. It supports both round and rectangular ductwork, offering precise calculations through direct entry or intuitive sliders. The tool provides live updates and outputs key performance metrics.
- Size round and rectangular ductwork
- Adjust airflow, diameter, width, and height
- Direct number entry for precision
- Lockable dimensions for 'what-if' scenarios
- Live update of calculated values
- Outputs velocity and pressure drop
- Supports IP and SI units
Read full descriptionHide full description
The Duct Calculator App for iPhone/iPad is a modern take on a the classic duct sizing wheel, allowing HVAC engineers, designers and contractors quickly and accurately size a new duct or calculate the performance of an existing duct on your iOS devices. Size both round and rectangular ductwork with the ease of a traditional Ductulator. Adjust the airflow, diameter, width or height sliders with your thumbs. Get maximum precision by entering numbers directly into the the calculator. Lock friction rate, diameter or width or height to make the calculations you need for your design. Live update of the calculated values allows you to see the impact of the changes immediately. Outputs velocity for both round and rectangular ducts. PERFORM QUICK AND ACCURATE CALCULATIONS: Enter the airflow and sizes in directly as numbers for maximum precision. - or - Use the airflow and size sliders for quick calculations. Shows live equivalent round/rectangular duct sizes. Specific dimensions can be locked to allow specific what-ifs to be quickly calculated. Works for both IP and SI units. You can select from a range of duct roughness categories. Designed to allow quick calculations anywhere, anytime, it is ideal for the HVAC designer or contractor. HOW TO USE: Locking Dimensions: The lock symbols to the right of the duct dimensions indicate if that particular dimension is locked when calculating new equivalent values when a dimension is updated. The Diameter can be locked or unlocked. The Width or Height can be locked, but not both. Using the Sliders: Move the sliders for Airflow, Duct Diameter, Width and Height up and down to match the desired duct size to calculate velocity and pressure drop for. The Diameter, Width and Height will change such that the equivalent size is shown: Changing the diameter will updated either the equivalent Width or the Height, depending on which dimension is unlocked. Changing the Width or Height will update the equivalent Diameter if it is unlocked, or the other rectangular duct dimension of the Diameter size is locked. Direct Entry: The values for Airflow, Diameter, Width and Height can be directly edited in the text boxes to allow quick entry of exact numbers. Invalid entries will generate an error message, and must be corrected prior to the calculations updating. Output: The values for the calculated Velocity for Round Duct and Rectangular Duct are shown, as is the Pressure Drop per Length value. NOTES: This application (App) is provided for use by qualified HVAC engineers and designers in the design of air handling systems and is not a substitute for appropriate design services. When in doubt, contact a design professional.
Quietflex Ductulator
This utility app helps HVAC professionals and enthusiasts quickly calculate essential airflow metrics for various duct sizes. It provides CFM, FPM, and FL values, simplifying HVAC system design and analysis.
- Calculate CFM
- Calculate FPM
- Calculate FL
- Supports different duct diameters
- HVAC system analysis
Read full descriptionHide full description
Use the Quietflex Ductulator app to calculate CFM, FPM, and FL of different diameter ducts.
Screenshots
Verdict
The clearest difference is price: Quietflex Ductulator at Free against Duct Calculator's $19.99. Quietflex Ductulator also leads on rating (5.0 vs 4.5) and update cadence (every 3 days vs every 2 months). Duct Calculator's advantage is ratings volume (189 vs 1). On ads, in-app purchases, monetization model and device support 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
Quietflex Ductulator is free to download; Duct Calculator costs $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Quietflex Ductulator holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: Duct Calculator has 189 ratings behind it against 1, so its average is the more settled of the two.
Duct Calculator ships an update every 2 months, Quietflex Ductulator every 3 days. The most recent releases landed on October 22, 2026 and September 26, 2026 respectively.
| Parameter | Duct Calculator | Quietflex Ductulator |
|---|---|---|
| Price | $19.99 | Free — better |
| Rating | 4.5 (189 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 57.1% of reviews | — |
| Number of ratings | 189 — better | 1 |
| Update frequency | Every 2 months | Every 3 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod, Mac — better | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 8.0 — better |
| Further details — not scored | ||
| Size | 2 MB | 30 MB |
| Age rating | 4+ | 4+ |
| Developer | Pheinex, LLC | Goodman Manufacturing L.P. |
Customer experience
Duct Calculator
Quietflex Ductulator
In-app purchases
Duct Calculator
No in-app purchases
Quietflex Ductulator
No in-app purchases
Questions
Is Duct Calculator free?
Is Quietflex Ductulator free?
Which has better reviews, Duct Calculator or Quietflex Ductulator?
Do Duct Calculator or Quietflex Ductulator have ads?
Which is updated more often, Duct Calculator or Quietflex Ductulator?
Other comparisons















