# Frontier X vs Calibrex App

The clearest difference is rating: Frontier X at 4.6 against Calibrex App's 3.5. Frontier X also leads on review sentiment (82% vs 50%) and ratings volume (318 vs 11). Calibrex App's advantage is in-app purchases (none vs 2). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Frontier X sells 2 in-app purchases, starting at $14.99 per month. Calibrex App asks for nothing beyond the download.

Frontier X holds the better App Store score, 4.6 against 3.5. That said, the two scores are not equally well evidenced: Frontier X has 318 ratings behind it against 11, so its average is the more settled of the two. Written reviews point the same way: 82% of Frontier X's written reviews are positive against 50% of Calibrex App's.

Frontier X ships an update every 3 weeks, Calibrex App fortnightly. The most recent releases landed on October 25, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Frontier X | Calibrex App |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (318 ratings)](https://appshunter.io/ios/app/frontier-x/id1483444499/reviews)** | [3.5 (11 ratings)](https://appshunter.io/ios/app/calibrex-app/id6741951538/reviews) |
| Number of ratings | **318** | 11 |
| Positive reviews | **81.8% of reviews** | 50.0% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Fortnightly** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 569 MB | 150 MB |
| Requires iOS | 16.0 | **15.1** |
| Devices | iPhone, Apple Watch | **iPhone, iPad, iPod** |
| Age rating | 4+ | 12+ |
| Developer | [Fourthfrontier](https://appshunter.io/developer/1331846764) | [CalibrexInc](https://appshunter.io/developer/1485591463) |

## What reviewers say

### Frontier X

[App page](https://appshunter.io/ios/app/frontier-x/id1483444499)

Track your heart health and exercise performance with a smart chest strap monitor. Gain detailed insights into heart rate, rhythms, and training load. Receive personalized feedback and alerts to optimize your workouts and understand your body better.

**Highlights:** Heart Health Monitoring, Real-time Heart Rate & HRV, Breathing Rate & Strain Tracking, Activity Recording (24hrs), Personalized Vibration Alerts, AI-enabled Training Insights, Metabolic Profile Analytics (Premium)

**Features:** Apple Watch app

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $14.99 | per month |
| Yearly | $119.99 | per year |

**What reviewers like**

- 🚀 Amazing device
- 👍 Great HR data and insight
- 👍 Helpful in gaining more data
- 👍 Fantastic concept with excellent execution
- 👍 Loads of useful information

**What reviewers complain about**

- 🐛 Worse and worse as time goes by
- 🐛 ECG doesn't work
- 🐛 Chest strap issues, device keeps popping out
- 🐛 Paywalled functionality
- 🐛 Syncing issues, device keeps disconnecting

**Reported bugs**

- ECG stopped working
- Inaccurate breathing rate and other metrics
- Inability to edit activity details for indoor workouts
- Syncing issues with Garmin devices after firmware updates

**Requested features**

- Add interval markers
- Improve integration with Apple Fitness/Fitness+
- Add support for ANT+
- Improve compatibility with other fitness apps and devices
- Add more customization options for workouts


### Calibrex App

[App page](https://appshunter.io/ios/app/calibrex-app/id6741951538)

This wearable device precisely tracks your weightlifting reps, rest, and movements. It provides personalized insights into your training, offering live audio coaching and tailored workouts to help you achieve your strength, speed, or endurance goals.

**Highlights:** Precise rep, rest, and movement tracking, Live audio coaching tailored to goals, Personalized insights into training performance, Advanced tracking and tailored workouts, Set Score, Difficulty Score, Speed Score, Tempo Score, Discover training trends and program balance

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

**In-app purchases:** none


## Frequently asked questions

### Is Frontier X free?

Frontier X is free to download, with in-app purchases available.

### Is Calibrex App free?

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

### Which has better reviews, Frontier X or Calibrex App?

Frontier X is rated higher. Frontier X averages 4.6 out of 5 from 318 ratings, while Calibrex App averages 3.5 from 11 ratings.

### Do Frontier X or Calibrex App have ads?

Neither Frontier X nor Calibrex App shows ads.

### Which is updated more often, Frontier X or Calibrex App?

Frontier X ships an update every 3 weeks, and Calibrex App fortnightly. Most recently, Frontier X was updated on October 25, 2026 and Calibrex App on October 24, 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.*