# nitroxCalc vs Mares App

The clearest difference is in-app purchases: nitroxCalc at none against Mares App's 8. nitroxCalc also leads on iOS requirement (9.0 vs 16.6). Mares App's advantage is update cadence (every 3 weeks vs every 18 months). On price, ads and device support there is nothing between them.

Both are free to download. Mares App sells 8 in-app purchases, starting at $2.99 per month. nitroxCalc asks for nothing beyond the download.

nitroxCalc ships an update every 18 months, Mares App every 3 weeks. The most recent releases landed on September 8, 2026 and September 21, 2026 respectively.

## The numbers

| Metric | nitroxCalc | Mares App |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.5 (183 ratings)](https://appshunter.io/ios/app/mares-app/id1625641063/reviews)** |
| Number of ratings | — | **183** |
| Positive reviews | — | 47.5% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 18 months | **Every 3 weeks** |
| Monetization | — | Free with in-app purchases |
| Size | 5 MB | 247 MB |
| Requires iOS | **9.0** | 16.6 |
| Devices | iPhone, iPod | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 4+ |
| Developer | [CAP-REL](https://appshunter.io/developer/1405536766) | [Head Watersports S.p.A.](https://appshunter.io/developer/1193522423) |

## What reviewers say

### nitroxCalc

[App page](https://appshunter.io/ios/app/nitroxcalc/id1408060704)

**Features:** macOS Compatibility

**In-app purchases:** none


### Mares App

[App page](https://appshunter.io/ios/app/mares-app/id1625641063)

Transform your Apple Watch Ultra into a dive computer, recording dives directly on your wrist. Log scuba, freediving, and technical dives, manage dive sites, and track underwater wildlife sightings. Share your adventures with dive buddies and keep your equipment details organized.

**Highlights:** Apple Watch Ultra dive computer integration, Digital dive logbook, Dive site database and management, Underwater wildlife tracking, Dive buddy sharing, Dive equipment management, Firmware updates

**Features:** macOS Compatibility, Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (8)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Snorkel Only | $2.99 | per month |
| Full Featured Month (Housing Only) | $6.99 | per month |
| Full Featured Month (Ultra Only) | $6.99 | per month |
| MARES Fully Featured Monthly | $8.99 | per month |
| Full Featured Yearly (Housing Only) | $49.99 | per year |
| Full Featured Yearly (Ultra Only) | $49.99 | per year |
| MARES Fully Featured Yearly | $69.99 | per year |
| MARES Fully Featured Yearly Family | $119.99 | per year |


## Frequently asked questions

### Is nitroxCalc free?

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

### Is Mares App free?

Mares App is free to download, with in-app purchases available.

### Do nitroxCalc or Mares App have ads?

Neither nitroxCalc nor Mares App shows ads.

### Which is updated more often, nitroxCalc or Mares App?

nitroxCalc ships an update every 18 months, and Mares App every 3 weeks. Most recently, nitroxCalc was updated on September 8, 2026 and Mares App on September 21, 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.*