Subsurface vs Gas Blender Toolkit
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Subsurface
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.
- Mobile dive log management
- Edit dive data
- Download from Bluetooth LE dive computers
- Optional cloud synchronization
- Open-source and free
Read full descriptionHide full description
Subsurface-mobile is an iOS dive log application based on Subsurface, the best free open source dive log application available on Windows, Mac and Linux. Subsurface-mobile allows you to access your dive log on your tablet or phone, edit the data and even download new dive information from many Bluetooth LE enabled dive computers. Using a free Subsurface Cloud Storage account you can synchronize your dive data with the Subsurface desktop application (while significantly increasing the usefulness, the cloud account is not required to use Subsurface-mobile). To get support from the developers, please use the in-app menu entry "Ask for support" Please check out the Subsurface-mobile user manual: https://subsurface-divelog.org/documentation/subsurface-mobile-v3-user-manual (also available from within the app) Subsurface-mobile is free and open source. No ads, no commercial anything. And it comes with free cloud storage (if you decide to use that - it's optional). Your data aren't used for anything, nothing gets monetized.
Gas Blender Toolkit
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.
- Partial pressure blending
- Continuous blending
- Trimix, nitrox, heliox calculations
- Ideal and real gas models
- Cost calculation
- Top off from storage
Read full descriptionHide full description
Gas Blender Toolkit is a comprehensive, purpose-built calculator for technical and recreational scuba divers who blend their own breathing gases. FUNCTIONS • Partial-pressure gas blending with freely configurable fill order • Continuous / delta-gas blending method • Decanting from a storage bank, with calculation of the number of possible fills • MOD / END tables for standard scuba gases • pSCR loop oxygen-reduction calculation at constant volume ratio • CCR rebreather diluent END calculator for any depth and chosen PPO2 setpoint FEATURES • Real gas (Van der Waals) or ideal gas calculations • Cost calculation for each gas fill • Fully customizable standard gas list • Accounts for gas heating during filling • Clean, fast and easy to use • Available in English, German, Russian and Spanish Gas Blender Toolkit is the completely rewritten successor to the DIR-Wetnotes app, redesigned from the ground
Screenshots
Verdict
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 iOS requirement (15.0 vs 17). On review sentiment, ads, in-app purchases and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Subsurface | Gas Blender Toolkit |
|---|---|---|
| Price | Free — better | $2.99 |
| Rating | 4.5 (48 ratings) — better | 3.0 (2 ratings) |
| Positive reviews | 63.3% of reviews — better | 60.0% of reviews |
| Number of ratings | 48 — better | 2 |
| Update frequency | Every 2 months | Every 9 days — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17 | 15.0 — better |
| Further details — not scored | ||
| Size | 52 MB | 3 MB |
| Age rating | 4+ | 4+ |
| Developer | Dirk Hohndel | Oleg Gurevich |
Customer experience
Subsurface
Gas Blender Toolkit
In-app purchases
Subsurface
No in-app purchases
Gas Blender Toolkit
No in-app purchases
Questions
Is Subsurface free?
Is Gas Blender Toolkit free?
Which has better reviews, Subsurface or Gas Blender Toolkit?
Do Subsurface or Gas Blender Toolkit have ads?
Which is updated more often, Subsurface or Gas Blender Toolkit?
Other comparisons
