# Alveolar vs VentRef

The clearest difference is update cadence: VentRef at every 3 weeks against Alveolar's every 4 months. VentRef also leads on ratings volume (44 vs 1) and review sentiment (100% vs 89%). Alveolar's advantage is iOS requirement (8.0 vs 26.0). On price, rating, 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.

On the App Store both sit at effectively the same score — 5.0 for Alveolar against 5.0 for VentRef. That said, the two scores are not equally well evidenced: VentRef has 44 ratings behind it against 1, so its average is the more settled of the two. Written reviews are what separate them: 89% of Alveolar's written reviews are positive against 100% of VentRef's.

Alveolar ships an update every 4 months, VentRef every 3 weeks. The most recent releases landed on October 15, 2026 and October 10, 2026 respectively.

## The numbers

| Metric | Alveolar | VentRef |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/alveolar-arterial-a-a-gradient/id996385661/reviews) | [5.0 (44 ratings)](https://appshunter.io/ios/app/ventref/id6756503414/reviews) |
| Number of ratings | 1 | **44** |
| Positive reviews | 88.9% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 3 weeks** |
| Monetization | Free | Free |
| Size | 16 MB | 27 MB |
| Requires iOS | **8.0** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 17+ | 17+ |
| Developer | [Satish Deopujari](https://appshunter.io/developer/1180072702) | [Rishi Kumar](https://appshunter.io/developer/1434016052) |

## What reviewers say

### Alveolar

[App page](https://appshunter.io/ios/app/alveolar-arterial-a-a-gradient/id996385661)

This app calculates the alveolar-arterial oxygen gradient (A-a gradient) and the PaO2/FiO2 ratio. It provides formulas and explanations for these important respiratory measurements, useful for medical professionals and students.

**Highlights:** Alveolar-arterial oxygen gradient calculation, PaO2/FiO2 ratio calculation, Formulas for PAO2 and A-a gradient, Educational explanations of respiratory measurements, Supports room air and variable FiO2

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

**In-app purchases:** none


### VentRef

[App page](https://appshunter.io/ios/app/ventref/id6756503414)

A clinical reference tool for healthcare professionals managing mechanical ventilation and oxygen therapy. It provides information grounded in respiratory physiology and evidence-based critical care.

**Highlights:** Mechanical ventilation reference, Oxygen therapy reference, Respiratory physiology, Evidence-based critical care, Clinical decision support

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

**In-app purchases:** none


## Frequently asked questions

### Is Alveolar free?

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

### Is VentRef free?

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

### Which has better reviews, Alveolar or VentRef?

Alveolar and VentRef are both rated 5.0 out of 5 on the App Store, from 1 and 44 ratings respectively.

### Do Alveolar or VentRef have ads?

Neither Alveolar nor VentRef shows ads.

### Which is updated more often, Alveolar or VentRef?

Alveolar ships an update every 4 months, and VentRef every 3 weeks. Most recently, Alveolar was updated on October 15, 2026 and VentRef 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.*