# Rotax MAX Jetting vs Fox + Son Jetmax

The clearest difference is review sentiment: Fox + Son Jetmax at 100% against Rotax MAX Jetting's 0%. Fox + Son Jetmax also leads on rating (5.0 vs 1.9) and iOS requirement (15.1 vs 17.0). Rotax MAX Jetting's advantage is in-app purchases (none vs 1) and ratings volume (8 vs 2). On price, update cadence, ads and device support there is nothing between them.

Both are free to download. Fox + Son Jetmax sells 1 in-app purchase, starting at $7.99 per year. Rotax MAX Jetting asks for nothing beyond the download.

Fox + Son Jetmax holds the better App Store score, 5.0 against 1.9. Both are backed by a comparable volume of ratings — 8 and 2 respectively. Written reviews point the same way: 0% of Rotax MAX Jetting's written reviews are positive against 100% of Fox + Son Jetmax's.

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on November 2, 2026 and November 5, 2026 respectively.

## The numbers

| Metric | Rotax MAX Jetting | Fox + Son Jetmax |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [1.9 (8 ratings)](https://appshunter.io/ios/app/rotax-max-jetting/id1152315347/reviews) | **[5.0 (2 ratings)](https://appshunter.io/ios/app/fox-plus-son-jetmax/id6748326003/reviews)** |
| Number of ratings | **8** | 2 |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | **Free** | Subscription |
| Size | 13 MB | 16 MB |
| Requires iOS | 17.0 | **15.1** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [BRP-Rotax GmbH & Co KG](https://appshunter.io/developer/1152315346) | [Trophy Inc.](https://appshunter.io/developer/1752591571) |

## What reviewers say

### Rotax MAX Jetting

[App page](https://appshunter.io/ios/app/rotax-max-jetting/id1152315347)

This app helps users find the ideal carburetor main jet size for Rotax kart engines. It calculates settings based on ambient conditions like temperature, altitude, and air pressure, either automatically via GPS or manually. Supports various Rotax MAX engine types.

**Highlights:** Optimal main jet calculation, Supports multiple Rotax MAX engines, Automatic GPS weather data, Manual ambient parameter entry, Celsius/Fahrenheit toggle, Meters/Feet toggle

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

**In-app purchases:** none


### Fox + Son Jetmax

[App page](https://appshunter.io/ios/app/fox-plus-son-jetmax/id6748326003)

This application simplifies jetting calculations for Rotax engines, factoring in weather and altitude. It provides racers with precise tuning recommendations, including relative horsepower and an interactive gear chart, to optimize performance on race day.

**Highlights:** Rotax engine jetting calculator, Weather and altitude adjustments, Relative horsepower calculation, Interactive gear chart, Rotax tuning tips

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Yearly | $7.99 | per year |


## Frequently asked questions

### Is Rotax MAX Jetting free?

Rotax MAX Jetting is free to download, with no in-app purchases.

### Is Fox + Son Jetmax free?

Fox + Son Jetmax is free to download, with in-app purchases available.

### Which has better reviews, Rotax MAX Jetting or Fox + Son Jetmax?

Fox + Son Jetmax is rated higher. Rotax MAX Jetting averages 1.9 out of 5 from 8 ratings, while Fox + Son Jetmax averages 5.0 from 2 ratings.

### Do Rotax MAX Jetting or Fox + Son Jetmax have ads?

Neither Rotax MAX Jetting nor Fox + Son Jetmax shows ads.

### Which is updated more often, Rotax MAX Jetting or Fox + Son Jetmax?

Rotax MAX Jetting ships an update every 3 months, and Fox + Son Jetmax every 3 months. Most recently, Rotax MAX Jetting was updated on November 2, 2026 and Fox + Son Jetmax on November 5, 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.*