# Rail Model Track Calc vs Spark Plug Reader

The clearest difference is in-app purchases: Rail Model Track Calc at none against Spark Plug Reader's 1. Spark Plug Reader's advantage is ads (none vs shown) and update cadence (every 2 days vs every 18 months). On price, device support and iOS requirement there is nothing between them.

Both are free to download. Spark Plug Reader sells 1 one-off in-app purchase. Rail Model Track Calc asks for nothing beyond the download.

Rail Model Track Calc ships an update every 18 months, Spark Plug Reader every 2 days. Both last shipped on October 6, 2026.

## The numbers

| Metric | Rail Model Track Calc | Spark Plug Reader |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.0 (1 ratings)](https://appshunter.io/ios/app/rail-model-track-calc/id1529070758/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 18 months | **Every 2 days** |
| Monetization | Ad-supported | — |
| Size | 9 MB | 37 MB |
| Requires iOS | **15.4** | 16.4 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Nobuyuki Kumakura](https://appshunter.io/developer/1529070760) | [EVREN YUCEBAS](https://appshunter.io/developer/6782353474) |

## What reviewers say

### Rail Model Track Calc

[App page](https://appshunter.io/ios/app/rail-model-track-calc/id1529070758)

Easily calculate horizontal and vertical dimensions for diagonal railroad model track layouts. Input track length and angle to get precise measurements for combining different track pieces. Avoid guesswork and ensure accurate model railway construction.

**Highlights:** Calculate horizontal and vertical track lengths, Input track length and angle, Precise measurements in 0.5 mm increments, Error margin less than 0.5mm, Reset function for calculations, Designed for railroad modeling hobbyists

**Features:** macOS Compatibility

**In-app purchases:** none


### Spark Plug Reader

[App page](https://appshunter.io/ios/app/spark-plug-reader/id6805215335)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full Version | $4.99 | one-time |


## Frequently asked questions

### Is Rail Model Track Calc free?

Rail Model Track Calc is free to download, with no in-app purchases.

### Is Spark Plug Reader free?

Spark Plug Reader is free to download, with in-app purchases available.

### Do Rail Model Track Calc or Spark Plug Reader have ads?

Rail Model Track Calc shows ads; Spark Plug Reader does not.

### Which is updated more often, Rail Model Track Calc or Spark Plug Reader?

Rail Model Track Calc ships an update every 18 months, and Spark Plug Reader every 2 days. Most recently, Rail Model Track Calc was updated on October 6, 2026 and Spark Plug Reader on October 6, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*