# O2 Duration vs Skytrackers NG

The clearest difference is price: Skytrackers NG at Free against O2 Duration's $2.99. Skytrackers NG also leads on update cadence (every 2 months vs every 15 months). O2 Duration's advantage is iOS requirement (7.0 vs 17.0). On ads, in-app purchases and device support there is nothing between them.

Skytrackers NG 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, Skytrackers NG every 2 months. The most recent releases landed on October 15, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | O2 Duration | Skytrackers NG |
| --- | --- | --- |
| 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 2 months** |
| Monetization | Paid | — |
| Size | 1 MB | 65 MB |
| Requires iOS | **7.0** | 17.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Advanced Aviation LLC](https://appshunter.io/developer/540245667) | [Skytec Inc.](https://appshunter.io/developer/730811019) |

## 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


### Skytrackers NG

[App page](https://appshunter.io/ios/app/skytrackers-ng/id1065714415)

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

**In-app purchases:** none


## Frequently asked questions

### Is O2 Duration free?

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

### Is Skytrackers NG free?

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

### Do O2 Duration or Skytrackers NG have ads?

Neither O2 Duration nor Skytrackers NG shows ads.

### Which is updated more often, O2 Duration or Skytrackers NG?

O2 Duration ships an update every 15 months, and Skytrackers NG every 2 months. Most recently, O2 Duration was updated on October 15, 2026 and Skytrackers NG on October 20, 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.*