# Propeller Calc vs Gobius

The clearest difference is review sentiment: Propeller Calc at 100% against Gobius's 0%. Propeller Calc also leads on rating (3.0 vs 1.0). Gobius's advantage is update cadence (monthly vs every 21 months) and iOS requirement (15.0 vs 17.0). On price, ratings volume, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Propeller Calc holds the better App Store score, 3.0 against 1.0. Both are backed by a comparable volume of ratings — 1 and 2 respectively. Written reviews point the same way: 100% of Propeller Calc's written reviews are positive against 0% of Gobius's.

Propeller Calc ships an update every 21 months, Gobius monthly. The most recent releases landed on September 26, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | Propeller Calc | Gobius |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.0 (1 ratings)](https://appshunter.io/ios/app/propeller-calc/id478119478/reviews)** | [1.0 (2 ratings)](https://appshunter.io/ios/app/gobius/id6471569744/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | **100.0% of reviews** | 0.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 21 months | **Monthly** |
| Monetization | Free | Free |
| Size | 3 MB | 34 MB |
| Requires iOS | 17.0 | **15.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Frode Rørvik](https://appshunter.io/developer/478119481) | [Gobius Sensor Technology AB](https://appshunter.io/developer/1422407278) |

## What reviewers say

### Propeller Calc

[App page](https://appshunter.io/ios/app/propeller-calc/id478119478)

This utility calculates propeller performance metrics like pitch, gear ratio, RPM, slip, and speed. Input any four values, and the app computes the fifth, helping users understand the relationship between propeller design and boat performance.

**Highlights:** Calculate pitch, gear ratio, RPM, slip, and speed, Enter any four variables to find the fifth, Understand propeller slip and its impact, Supports iPhone and iPad, Free to use

**Features:** macOS Compatibility

**In-app purchases:** none


### Gobius

[App page](https://appshunter.io/ios/app/gobius/id6471569744)

This application works with specific sensors to monitor fluid levels in tanks, displaying volume in percentages and liters. It provides installation guides, tank calculators for various shapes, and visual level indicators.

**Highlights:** Fluid level monitoring, Volume display in % and liters, Installation guides, Tank calculator for non-rectangular tanks, Visual fluid level indicators, Waterproof sensor compatibility

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

**In-app purchases:** none


## Frequently asked questions

### Is Propeller Calc free?

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

### Is Gobius free?

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

### Which has better reviews, Propeller Calc or Gobius?

Propeller Calc is rated higher. Propeller Calc averages 3.0 out of 5 from 1 ratings, while Gobius averages 1.0 from 2 ratings.

### Do Propeller Calc or Gobius have ads?

Neither Propeller Calc nor Gobius shows ads.

### Which is updated more often, Propeller Calc or Gobius?

Propeller Calc ships an update every 21 months, and Gobius monthly. Most recently, Propeller Calc was updated on September 26, 2026 and Gobius on October 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.*