# Engine RPM vs AirmarCAST™

The clearest difference is price: AirmarCAST™ at Free against Engine RPM's $8.99. AirmarCAST™ also leads on update cadence (every 3 months vs every 16 months). Engine RPM's advantage is rating (4.0 vs 2.6) and review sentiment (48% vs 25%). On ads, in-app purchases, monetization model and device support there is nothing between them.

AirmarCAST™ is free to download; Engine RPM costs $8.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Engine RPM holds the better App Store score, 4.0 against 2.6. That said, the two scores are not equally well evidenced: Engine RPM has 35 ratings behind it against 5, so its average is the more settled of the two. Written reviews point the same way: 48% of Engine RPM's written reviews are positive against 25% of AirmarCAST™'s.

Engine RPM ships an update every 16 months, AirmarCAST™ every 3 months. The most recent releases landed on November 1, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | Engine RPM | AirmarCAST™ |
| --- | --- | --- |
| Price | $8.99 | **Free** |
| Rating | **[4.0 (35 ratings)](https://appshunter.io/ios/app/engine-rpm/id340401811/reviews)** | [2.6 (5 ratings)](https://appshunter.io/ios/app/airmarcast/id1492428585/reviews) |
| Number of ratings | **35** | 5 |
| Positive reviews | **47.7% of reviews** | 25.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 16 months | **Every 3 months** |
| Monetization | Free | Free |
| Size | 3 MB | 112 MB |
| Requires iOS | **13.0** | 16 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Real-Time Specialties](https://appshunter.io/developer/335568332) | [Airmar Technology Inc.](https://appshunter.io/developer/1062316789) |

## What reviewers say

### Engine RPM

[App page](https://appshunter.io/ios/app/engine-rpm/id340401811)

Analyze engine sound to calculate RPM using advanced signal processing. Ideal for engine setup and diagnostics, it supports various engine types and provides real-time feedback for accurate readings.

**Highlights:** Acoustic RPM measurement, Engine sound analysis, Supports 2-stroke/4-stroke engines, Configurable cylinder count, Real-time autocorrelation graph, Adjustable update periods, Low-pass filtering

**Features:** Vision Pro support

**In-app purchases:** none

**What reviewers like**

- 💰 Saves money vs. dedicated tachometer
- 🛠️ Useful for engine tuning/diagnostics
- ✅ Works well with correct settings
- 🏎️ Accurate for steady RPMs
- 💡 Ingenious app concept

**What reviewers complain about**

- 📉 Inaccurate or unreliable readings
- ❓ Difficult to configure/use
- 💸 Waste of money (for many)
- 😵 Confusing interface/settings
- ⚡ Not good for rapidly changing RPMs

**Reported bugs**

- Does not register live RPM readings
- Displays incorrect or random numbers
- App opens then closes immediately
- Blank display or flashes incorrect data intermittently
- Cannot get consistent readings

**Requested features**

- Save configuration settings
- Option to display cycle/cylinder count on home screen
- Improved response time for transient surges
- Simplified or automated setup process
- Auto-scaling graphical display for easier harmonic matching


### AirmarCAST™

[App page](https://appshunter.io/ios/app/airmarcast/id1492428585)

Configure and calibrate your boat's Bluetooth-enabled multisensors and modules directly from your mobile device. View real-time data on detailed gauges and perform advanced calibrations for speed, temperature, and attitude without extra hardware.

**Highlights:** Bluetooth sensor connection, Real-time data display, Intuitive navigation, Speed, temperature, attitude calibration, On-board GPS speed comparison, Advanced speed calibration wizards

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

**In-app purchases:** none


## Frequently asked questions

### Is Engine RPM free?

Engine RPM costs $8.99, with no in-app purchases.

### Is AirmarCAST™ free?

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

### Which has better reviews, Engine RPM or AirmarCAST™?

Engine RPM is rated higher. Engine RPM averages 4.0 out of 5 from 35 ratings, while AirmarCAST™ averages 2.6 from 5 ratings.

### Do Engine RPM or AirmarCAST™ have ads?

Neither Engine RPM nor AirmarCAST™ shows ads.

### Which is updated more often, Engine RPM or AirmarCAST™?

Engine RPM ships an update every 16 months, and AirmarCAST™ every 3 months. Most recently, Engine RPM was updated on November 1, 2026 and AirmarCAST™ on November 3, 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.*