# O2 Duration vs Clinical Protocols

The clearest difference is price: Clinical Protocols at Free against O2 Duration's $2.99. O2 Duration's advantage is iOS requirement (7.0 vs 15.0). On update cadence, ads, in-app purchases and device support there is nothing between them.

Clinical Protocols is free to download; O2 Duration costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

O2 Duration ships an update every 15 months, Clinical Protocols every 18 months. The most recent releases landed on September 30, 2026 and October 4, 2026 respectively.

## The numbers

| Metric | O2 Duration | Clinical Protocols |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | **[1.0 (1 ratings)](https://appshunter.io/ios/app/o2-duration/id556420187/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 15 months** | Every 18 months |
| Monetization | Paid | — |
| Size | 1 MB | 44 MB |
| Requires iOS | **7.0** | 15.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Advanced Aviation LLC](https://appshunter.io/developer/540245667) | [Tactuum, LLC](https://appshunter.io/developer/867012029) |

## What reviewers say

### O2 Duration

[App page](https://appshunter.io/ios/app/o2-duration/id556420187)

Calculate the approximate remaining oxygen in portable cylinders. Select your tank size, input current pressure and desired flow rate to see duration in minutes. Features a timer with alerts for low pressure.

**Highlights:** Oxygen cylinder duration calculation, Supports multiple cylinder sizes (A, B, D, E, G, H, K, M), Input current tank pressure, Input desired flow rate, Displays duration in minutes, Running timer with remaining time, Low pressure alerts (500lbs and 0lbs)

**Features:** macOS Compatibility

**In-app purchases:** none


### Clinical Protocols

[App page](https://appshunter.io/ios/app/clinical-protocols/id1327262364)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is O2 Duration free?

O2 Duration costs $2.99, with no in-app purchases.

### Is Clinical Protocols free?

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

### Do O2 Duration or Clinical Protocols have ads?

Neither O2 Duration nor Clinical Protocols shows ads.

### Which is updated more often, O2 Duration or Clinical Protocols?

O2 Duration ships an update every 15 months, and Clinical Protocols every 18 months. Most recently, O2 Duration was updated on September 30, 2026 and Clinical Protocols on October 4, 2026.

---

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