# Greenheck Toolbox vs Duct Calculator

The clearest difference is review sentiment: Duct Calculator at 57% against Greenheck Toolbox's 0%. Duct Calculator also leads on rating (4.5 vs 3.0) and ratings volume (189 vs 2). Greenheck Toolbox's advantage is price (Free vs $19.99) and iOS requirement (7.0 vs 15.0). On update cadence, ads, in-app purchases and monetization model there is nothing between them.

Greenheck Toolbox is free to download; Duct Calculator costs $19.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Duct Calculator holds the better App Store score, 4.5 against 3.0. That said, the two scores are not equally well evidenced: Duct Calculator has 189 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 0% of Greenheck Toolbox's written reviews are positive against 57% of Duct Calculator's.

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 1, 2026 and November 2, 2026 respectively.

## The numbers

| Metric | Greenheck Toolbox | Duct Calculator |
| --- | --- | --- |
| Price | **Free** | $19.99 |
| Rating | [3.0 (2 ratings)](https://appshunter.io/ios/app/greenheck-toolbox/id526779916/reviews) | **[4.5 (189 ratings)](https://appshunter.io/ios/app/duct-calculator/id1078238132/reviews)** |
| Number of ratings | 2 | **189** |
| Positive reviews | 0.0% of reviews | **57.1% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | Every 2 months |
| Monetization | Free | Free |
| Size | 2 MB | 2 MB |
| Requires iOS | **7.0** | 15.0 |
| Devices | iPhone, iPad, iPod | **iPhone, iPad, iPod, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [Greenheck](https://appshunter.io/developer/526779919) | [Pheinex, LLC](https://appshunter.io/developer/996932317) |

## What reviewers say

### Greenheck Toolbox

[App page](https://appshunter.io/ios/app/greenheck-toolbox/id526779916)

This utility app provides two essential tools for HVAC professionals: a Fan Law Calculator to adjust fan performance based on changes in speed, and a Ductulator to quickly size ductwork. Easily calculate and determine duct dimensions and airflow with various input parameters.

**Highlights:** Fan Law Calculator, Ductulator App, Adjust fan performance, Size HVAC ductwork, Calculate airflow, Determine duct dimensions

**Features:** macOS Compatibility

**In-app purchases:** none


### Duct Calculator

[App page](https://appshunter.io/ios/app/duct-calculator/id1078238132)

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.

**Highlights:** 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

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Greenheck Toolbox free?

Greenheck Toolbox is free to download, with no in-app purchases.

### Is Duct Calculator free?

Duct Calculator costs $19.99, with no in-app purchases.

### Which has better reviews, Greenheck Toolbox or Duct Calculator?

Duct Calculator is rated higher. Greenheck Toolbox averages 3.0 out of 5 from 2 ratings, while Duct Calculator averages 4.5 from 189 ratings.

### Do Greenheck Toolbox or Duct Calculator have ads?

Neither Greenheck Toolbox nor Duct Calculator shows ads.

### Which is updated more often, Greenheck Toolbox or Duct Calculator?

Greenheck Toolbox ships an update every 2 months, and Duct Calculator every 2 months. Most recently, Greenheck Toolbox was updated on November 1, 2026 and Duct Calculator on November 2, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*