# Propeller Calc vs Video tachometer

The clearest difference is rating: Video tachometer at 4.6 against Propeller Calc's 3.0. Video tachometer also leads on update cadence (every 3 months vs every 21 months) and ratings volume (84 vs 1). Propeller Calc's advantage is in-app purchases (none vs 1) and review sentiment (100% vs 85%). On price, ads and device support there is nothing between them.

Both are free to download. Video tachometer sells 1 one-off in-app purchase. Propeller Calc asks for nothing beyond the download.

Video tachometer holds the better App Store score, 4.6 against 3.0. That said, the two scores are not equally well evidenced: Video tachometer has 84 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 100% of Propeller Calc's written reviews are positive against 85% of Video tachometer's, so the app with the better star average is not the one people write more warmly about.

Propeller Calc ships an update every 21 months, Video tachometer every 3 months. The most recent releases landed on September 9, 2026 and September 10, 2026 respectively.

## The numbers

| Metric | Propeller Calc | Video tachometer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.0 (1 ratings)](https://appshunter.io/ios/app/propeller-calc/id478119478/reviews) | **[4.6 (84 ratings)](https://appshunter.io/ios/app/video-tachometer/id1492583587/reviews)** |
| Number of ratings | 1 | **84** |
| Positive reviews | **100.0% of reviews** | 84.6% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 21 months | **Every 3 months** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 3 MB | 5 MB |
| Requires iOS | 17.0 | **15.6** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Frode Rørvik](https://appshunter.io/developer/478119481) | [Dmitriy Kharutskiy](https://appshunter.io/developer/817385891) |

## 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


### Video tachometer

[App page](https://appshunter.io/ios/app/video-tachometer/id1492583587)

This app uses slow-motion video to create a strobe light effect, allowing you to measure rotational speeds. It records video with detailed information like frame rate and exposure, and offers customizable text overlays.

**Highlights:** Strobe light effect simulation, Rotational speed measurement (RPM/Hz), Slow-motion video recording, Customizable text overlays on video, Adjustable frame rate and exposure, Records 4K video (if supported)

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full version | $2.99 | one-time |


## Frequently asked questions

### Is Propeller Calc free?

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

### Is Video tachometer free?

Video tachometer is free to download, with in-app purchases available.

### Which has better reviews, Propeller Calc or Video tachometer?

Video tachometer is rated higher. Propeller Calc averages 3.0 out of 5 from 1 ratings, while Video tachometer averages 4.6 from 84 ratings.

### Do Propeller Calc or Video tachometer have ads?

Neither Propeller Calc nor Video tachometer shows ads.

### Which is updated more often, Propeller Calc or Video tachometer?

Propeller Calc ships an update every 21 months, and Video tachometer every 3 months. Most recently, Propeller Calc was updated on September 9, 2026 and Video tachometer on September 10, 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.*