# Subsurface vs Gas Blender Toolkit

The clearest difference is price: Subsurface at Free against Gas Blender Toolkit's $2.99. Subsurface also leads on rating (4.5 vs 3.0) and ratings volume (48 vs 2). Gas Blender Toolkit's advantage is update cadence (every 9 days vs every 2 months) and chart position (#52 vs unranked). On review sentiment, ads, in-app purchases and device support there is nothing between them.

Subsurface is free to download; Gas Blender Toolkit costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Subsurface holds the better App Store score, 4.5 against 3.0. That said, the two scores are not equally well evidenced: Subsurface has 48 ratings behind it against 2, so its average is the more settled of the two. Written reviews point the same way: 63% of Subsurface's written reviews are positive against 60% of Gas Blender Toolkit's.

Subsurface ships an update every 2 months, Gas Blender Toolkit every 9 days. The most recent releases landed on October 22, 2026 and October 21, 2026 respectively.

## The numbers

| Metric | Subsurface | Gas Blender Toolkit |
| --- | --- | --- |
| Price | **Free** | $2.99 |
| Rating | **[4.5 (48 ratings)](https://appshunter.io/ios/app/subsurface-mobile/id1093217161/reviews)** | [3.0 (2 ratings)](https://appshunter.io/ios/app/gas-blender-toolkit/id1467768490/reviews) |
| Number of ratings | **48** | 2 |
| Positive reviews | **63.3% of reviews** | 60.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 months | **Every 9 days** |
| Monetization | **Free** | Paid |
| Best chart rank | — | **#52** |
| Size | 52 MB | 3 MB |
| Requires iOS | 17 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Dirk Hohndel](https://appshunter.io/developer/1093217160) | [Oleg Gurevich](https://appshunter.io/developer/1467768489) |

## What reviewers say

### Subsurface

[App page](https://appshunter.io/ios/app/subsurface-mobile/id1093217161)

This application allows divers to manage their dive logs on their mobile devices. It supports editing dive data and downloading new information from compatible dive computers. Optional cloud synchronization is available for seamless data transfer with desktop versions.

**Highlights:** Mobile dive log management, Edit dive data, Download from Bluetooth LE dive computers, Optional cloud synchronization, Open-source and free

**In-app purchases:** none


### Gas Blender Toolkit

[App page](https://appshunter.io/ios/app/gas-blender-toolkit/id1467768490)

**Currently charting:** #52 Top Paid · Sports (US App Store)

This comprehensive toolkit assists scuba divers in calculating and blending various gas mixtures like trimix, nitrox, and heliox. It offers features for both partial pressure and continuous blending, cost calculation, and utilizes ideal and real gas models for accuracy. Optimized for larger screens, it serves as a successor to a previous diving application.

**Highlights:** Partial pressure blending, Continuous blending, Trimix, nitrox, heliox calculations, Ideal and real gas models, Cost calculation, Top off from storage

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

**In-app purchases:** none


## Frequently asked questions

### Is Subsurface free?

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

### Is Gas Blender Toolkit free?

Gas Blender Toolkit costs $2.99, with no in-app purchases.

### Which has better reviews, Subsurface or Gas Blender Toolkit?

Subsurface is rated higher. Subsurface averages 4.5 out of 5 from 48 ratings, while Gas Blender Toolkit averages 3.0 from 2 ratings.

### Do Subsurface or Gas Blender Toolkit have ads?

Neither Subsurface nor Gas Blender Toolkit shows ads.

### Which is updated more often, Subsurface or Gas Blender Toolkit?

Subsurface ships an update every 2 months, and Gas Blender Toolkit every 9 days. Most recently, Subsurface was updated on October 22, 2026 and Gas Blender Toolkit on October 21, 2026.

---

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