# Propeller Calc

> Propeller performance calculator for pitch, gear ratio, RPM, slip, and speed. (iPhone/iPad app by Frode Rørvik.)

- Source: https://appshunter.io/ios/app/propeller-calc/id478119478 (this page in markdown: same URL + `.md`)
- Developer: [Frode Rørvik](https://appshunter.io/developer/478119481)
- Category: Utilities
- Price: Free
- Rating: 3.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 17.0 · 3 MB
- Languages: American English
- Released: 2011-11-11
- Data updated: 2026-06-05
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/propeller-calc/id478119478/reviews.md

## What is Propeller Calc?

This calculator can determine pitch, gear ratio, RPM, propeller slip and speed parameters. Enter any four variables, and it will calculate the fifth. Use the toggle switch to choose which field to calculate.

Pitch is the theoretical forward movement for one complete turn of the propeller. Every inch of the boat in contact with the water induces drag. Therefore, the distance travelled differs since the propeller is "slipping" behind the theoretical distance it should travel with each rotation. The difference between theory and reality is called slip.

Depending on your application, slip typically ranges between 5% and 20%. A lower number is only sometimes what you are after. Slip of a prop changes with operating conditions and is not a direct measure of efficiency. Please consult professionals for guidance.

Happy powerboating

## Key features

- 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

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/propeller-calc/id478119478/reviews.md

### 5/5 — Great App even for RC Boats

*2013-02-08*

I use this App for assistance with prop selection on my RC Nito Boats. Use ratio 1 (1:1) and the rest is simple. It works well for full size boats too.

## Frequently asked questions about Propeller Calc

### What can Propeller Calc calculate?

Propeller Calc can determine pitch, gear ratio, RPM, propeller slip, and speed parameters. You can input any four of these variables, and the app will calculate the fifth for you.

### Is Propeller Calc free to use?

Yes, Propeller Calc is completely free to download and use. There are no in-app purchases or advertisements.

### What devices does Propeller Calc support?

Propeller Calc is available for both iPhone and iPad devices.

### How often is Propeller Calc updated?

The app was last updated on July 9, 2025, indicating ongoing support and potential for future improvements. The current version is 3.2.

### What is the age rating for Propeller Calc?

Propeller Calc has an age rating of 4+, making it suitable for a wide range of users.

### What does propeller slip mean in Propeller Calc?

Propeller Calc helps you understand propeller slip, which is the difference between the theoretical distance a propeller should move and the actual distance it travels due to drag. This typically ranges from 5% to 20%.

### Who developed Propeller Calc?

Propeller Calc was developed by Frode Rørvik.

### What is the user rating for Propeller Calc?

Propeller Calc has a rating of 3.0 stars based on 1 rating.

## Version history (last 5 releases)

### 3.2 — 2025-07-09

GUI changes and minor enhancements.

### 3.1 — 2024-03-18

The UI is tweaked to enhance usability. Speed can now be changed using a stepper or a slider control.

### 3.0 — 2024-03-12

- Rebuilt from the ground up
- Toggle buttons for selection
- New colours
- Dark mode support
- Updated info page

### 2.1 — 2017-09-25

This app has been updated by Apple to display the Apple Watch app icon.

In this updated version for iOS10 you can play with the slider controls for slip and RPM. This version also supports iPad.

### 2.0 — 2013-12-24

- New iOS7 look and feel!
- Slider controls for RPM and slip

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-05.*