# Propeller Calc vs Haidi Classic

The clearest difference is iOS requirement: Haidi Classic at 11.0 against Propeller Calc's 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.

## The numbers

| Metric | Propeller Calc | Haidi Classic |
| --- | --- | --- |
| 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 | — |
| Monetization | Free | — |
| Size | 3 MB | 68 MB |
| Requires iOS | 17.0 | **11.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Frode Rørvik](https://appshunter.io/developer/478119481) | [Haidi Energy Tehcnogy Co., Ltd](https://appshunter.io/developer/1645467042) |

## 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


### Haidi Classic

[App page](https://appshunter.io/ios/app/haidi-classic/id6768482303)

**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 Haidi Classic free?

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

### Do Propeller Calc or Haidi Classic have ads?

Neither Propeller Calc nor Haidi Classic shows ads.

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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.*