# DuctChecker vs Triangle Calc A

The clearest difference is update cadence: DuctChecker at every 4 months against Triangle Calc A's every 56 months. DuctChecker also leads on iOS requirement (15.0 vs 26.0). Triangle Calc A's advantage is price ($0.99 vs $6.99). On ads, in-app purchases and device support there is nothing between them.

DuctChecker costs $6.99 and Triangle Calc A $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

DuctChecker ships an update every 4 months, Triangle Calc A every 56 months. Both last shipped on October 8, 2026.

## The numbers

| Metric | DuctChecker | Triangle Calc A |
| --- | --- | --- |
| Price | $6.99 | **$0.99** |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 4 months** | Every 56 months |
| Monetization | Paid | — |
| Size | 23 MB | 0 MB |
| Requires iOS | **15.0** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [AIR DESIGN, INC.](https://appshunter.io/developer/923430781) | [kohei yamane](https://appshunter.io/developer/1239055575) |

## What reviewers say

### DuctChecker

[App page](https://appshunter.io/ios/app/ductchecker/id933593987)

Easily calculate duct dimensions using various engineering methods like constant pressure, static pressure regain, total pressure, and velocity. This tool simplifies complex duct design calculations, typically found in flow diagrams or slide rules.

**Highlights:** Constant pressure method calculation, Static pressure regain method, Total pressure method, Velocity method, Duct dimension determination, Simplified duct design

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

**In-app purchases:** none


### Triangle Calc A

[App page](https://appshunter.io/ios/app/triangle-calc-a/id1582200016)

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

**In-app purchases:** none


## Frequently asked questions

### Is DuctChecker free?

DuctChecker costs $6.99, with no in-app purchases.

### Is Triangle Calc A free?

Triangle Calc A costs $0.99, with no in-app purchases.

### Do DuctChecker or Triangle Calc A have ads?

Neither DuctChecker nor Triangle Calc A shows ads.

### Which is updated more often, DuctChecker or Triangle Calc A?

DuctChecker ships an update every 4 months, and Triangle Calc A every 56 months. Most recently, DuctChecker was updated on October 8, 2026 and Triangle Calc A on October 8, 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.*