# ABG Expert vs ROX Index

The clearest difference is update cadence: ROX Index at every 3 weeks against ABG Expert's every 5 months. ROX Index also leads on rating (5.0 vs 4.8) and iOS requirement (11.0 vs 13.0). ABG Expert's advantage is ratings volume (9 vs 1). On price, review sentiment, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ROX Index holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: ABG Expert has 9 ratings behind it against 1, so its average is the more settled of the two. Written reviews split almost evenly too, at 100% and 100% positive.

ABG Expert ships an update every 5 months, ROX Index every 3 weeks. The most recent releases landed on October 20, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | ABG Expert | ROX Index |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.8 (9 ratings)](https://appshunter.io/ios/app/abg-expert/id885575488/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/rox-index/id1582208777/reviews)** |
| Number of ratings | **9** | 1 |
| Positive reviews | 100.0% of reviews | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 5 months | **Every 3 weeks** |
| Monetization | Free | Free |
| Size | 2 MB | 10 MB |
| Requires iOS | 13.0 | **11.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 12+ | 4+ |
| Developer | [Brian Dale Vander Werf MD Inc](https://appshunter.io/developer/1521935908) | [Satish Deopujari](https://appshunter.io/developer/1180072702) |

## What reviewers say

### ABG Expert

[App page](https://appshunter.io/ios/app/abg-expert/id885575488)

This medical tool provides accurate and flexible acid-base analysis for healthcare professionals. It offers detailed explanations, customizable ranges, and advanced features like anion gap correction and A-a gradient adjustments for various patient conditions and locations.

**Highlights:** Validated accuracy with real-world testing, Plausibility checks for physiologically impossible data, Automatic anion gap correction with albumin, Detailed explanations with equations, Separate or combined analysis of ABG, anion gap, A-a gradient, Customizable normal ranges for anion gap and delta gap, Age and barometric pressure adjustments for A-a gradient, Support for SI and non-SI units, Color-coded results and differential diagnoses, Adjustments for chronic respiratory conditions

**Features:** macOS Compatibility

**In-app purchases:** none


### ROX Index

[App page](https://appshunter.io/ios/app/rox-index/id1582208777)

This medical app assists doctors and students in calculating the ROX index, a tool to predict the success or failure of High-Flow Nasal Cannula (HFNC) therapy, primarily studied in pneumonia patients. It simplifies the calculation using SpO2, FiO2, and Respiratory Rate.

**Highlights:** ROX index calculation, Predicts HFNC success/failure, Primarily for pneumonia patients, Uses SpO2, FiO2, and RR, Assists doctors and medical students

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is ABG Expert free?

ABG Expert is free to download, with no in-app purchases.

### Is ROX Index free?

ROX Index is free to download, with no in-app purchases.

### Which has better reviews, ABG Expert or ROX Index?

ROX Index is rated higher. ABG Expert averages 4.8 out of 5 from 9 ratings, while ROX Index averages 5.0 from 1 ratings.

### Do ABG Expert or ROX Index have ads?

Neither ABG Expert nor ROX Index shows ads.

### Which is updated more often, ABG Expert or ROX Index?

ABG Expert ships an update every 5 months, and ROX Index every 3 weeks. Most recently, ABG Expert was updated on October 20, 2026 and ROX Index on October 10, 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.*