Comparison

Trimix Tools vs Subsurface

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Trimix Tools

This app provides essential tools for divers to plan and blend Trimix gases. It calculates optimal mixes based on depth, oxygen partial pressure, and equivalent narcotic depth, and supports various cylinder filling scenarios. Calculations are available offline and can be customized with saved settings.

Highlights
  • Trimix blending and planning
  • Depth and partial pressure calculations
  • Equivalent Narcotic Depth (END) calculation
  • Saltwater and freshwater support
  • Cylinder filling and bleed down calculations
  • Metric and Imperial system support
  • Offline functionality
  • Saved settings and custom mixes
Features
Read full description

Trimix blending and planning tools that can be used where you are and when you need them. You can use these tools to plan your mixes prior to arriving at the dive shop or to fill your cylinder at the air station or on the boat. Calculations are provided for the best Trimix given a planned depth and a desired maximum partial pressure of oxygen and equivalent narcotic depth (END). You can also calculate the ceiling and maximum depths along with your END based on your planned mix. The dive planning tools support both salt water and fresh water calculations. The blending tools provide for filling a cylinder with a remaining mix (or empty) to a specified target mix using oxygen, helium and a topping mix (air or another available mix). You can also calculate the result of topping an existing partially filled cylinder with a specific topping mix (air or another available mix). There is also a Bleed Down calculator that allows you adjust an existing full or partially full cylinder to a new mix with minimal wasted gas. Trimix Tools supports calculations in both metric and Imperial/US systems of measure. Traveling on a boat or working out of network range? These tools are at hand any time you have your iPhone, iPad or iPod touch. You could, for example, easily calculate the result of topping your cylinder from your first dive with air from the boat's compressor to take advantage of any remaining mix. You also have the convenience of saved settings that you can recall at a touch and adjust to a new situation as needed. Chances are you regularly work with a specific set of mixes and common dive situations. Trimix Tools includes the convenience of saved settings that you can recall and adjust to a new situation as needed. You can also select mix values using pre-installed default mixes or your own saved custom mixes. When updating one of the mixes for a tool you are offered a list of saved mixes that you can use directly or adjust as needed. You can save the currently displayed mix by tapping on the "+" button. Just like with the saved calculations, you can re-arrange or delete any mixes in your saved list. Do you need to share your planning or blending calculations with other divers? All the tools have the ability to share the results of the calculations from within the application. You can set default email addresses and a subject Trimix Tool's settings that will be automatically added when you share a result. All END calculations (Dive Planning and Best Trimix tabs) in Trimix Tools treat oxygen as a narcotic gas by default. There is an option available under the Settings tab to change the default so that oxygen is not treated as narcotic if that is your preference. Remember you must always personally analyze your mix before diving it. This application is not a substitute for proper training and should not be used as a substitute for proper dive planning or the primary Trimix blending and planning methods taught during training. Please do not attempt to handle high pressure oxygen or fill SCUBA cylinders without proper training.

About

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.

Highlights
  • Mobile dive log management
  • Edit dive data
  • Download from Bluetooth LE dive computers
  • Optional cloud synchronization
  • Open-source and free
Read 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.

Screenshots

Trimix Tools4 screens
Subsurface4 screens

Verdict

The call

The clearest difference is price: Subsurface at Free against Trimix Tools's $6.99. Subsurface also leads on ratings volume (48 vs 5). Trimix Tools's advantage is rating (5.0 vs 4.5) and review sentiment (100% vs 63%). On update cadence, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Subsurface is free to download; Trimix Tools costs $6.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Trimix Tools holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: Subsurface has 48 ratings behind it against 5, so its average is the more settled of the two. Written reviews point the same way: 100% of Trimix Tools's written reviews are positive against 63% of Subsurface's.

UpkeepUpdate frequency

Trimix Tools ships an update every 4 months, Subsurface every 2 months. The most recent releases landed on November 6, 2026 and November 2, 2026 respectively.

Scorecard7 real differences · 3 level
Trimix Tools versus Subsurface: the parameters behind the verdict, then further details
ParameterTrimix ToolsSubsurface
Price$6.99Free — better
Rating5.0 (5 ratings) — better4.5 (48 ratings)
Positive reviews100.0% of reviews — better63.3% of reviews
Number of ratings548 — better
Update frequencyEvery 4 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPad, iPod, Mac — betteriPhone, iPad
Requires iOS15.6 — better17
Further details — not scored
Size6 MB52 MB
Age rating4+4+
DeveloperGreg MclaughlinDirk Hohndel

Customer experience

Trimix Tools

All ratings5 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews11 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Subsurface

All ratings48 ratings
Positive89.6%
Neutral2.1%
Negative8.3%
Written reviews30 reviews
Positive63.3%
Neutral6.7%
Negative30.0%

In-app purchases

None

Trimix Tools

No in-app purchases

None

Subsurface

No in-app purchases

Questions

Is Trimix Tools free?
Trimix Tools costs $6.99, with no in-app purchases.
Is Subsurface free?
Subsurface is free to download, with no in-app purchases.
Which has better reviews, Trimix Tools or Subsurface?
Trimix Tools is rated higher. Trimix Tools averages 5.0 out of 5 from 5 ratings, while Subsurface averages 4.5 from 48 ratings.
Do Trimix Tools or Subsurface have ads?
Neither Trimix Tools nor Subsurface shows ads.
Which is updated more often, Trimix Tools or Subsurface?
Trimix Tools ships an update every 4 months, and Subsurface every 2 months. Most recently, Trimix Tools was updated on November 6, 2026 and Subsurface on November 2, 2026.

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