# Propeller Calc vs ENGINE SFC

The clearest difference is update cadence: ENGINE SFC at daily against Propeller Calc's every 21 months. ENGINE SFC also leads on iOS requirement (15.2 vs 17.0). On price, ads, in-app purchases and device support 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 ships an update every 21 months, ENGINE SFC daily. The most recent releases landed on September 9, 2026 and September 11, 2026 respectively.

## The numbers

| Metric | Propeller Calc | ENGINE SFC |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.0 (1 ratings)](https://appshunter.io/ios/app/propeller-calc/id478119478/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 21 months | **Daily** |
| Monetization | Free | — |
| Size | 3 MB | 6 MB |
| Requires iOS | 17.0 | **15.2** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Frode Rørvik](https://appshunter.io/developer/478119481) | [Oleksii Nezhalskyi](https://appshunter.io/developer/1687730603) |

## 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


### ENGINE SFC

[App page](https://appshunter.io/ios/app/engine-sfc/id6469806252)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Propeller Calc free?

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

### Is ENGINE SFC free?

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

### Do Propeller Calc or ENGINE SFC have ads?

Neither Propeller Calc nor ENGINE SFC shows ads.

### Which is updated more often, Propeller Calc or ENGINE SFC?

Propeller Calc ships an update every 21 months, and ENGINE SFC daily. Most recently, Propeller Calc was updated on September 9, 2026 and ENGINE SFC on September 11, 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.*