# Gengou vs Bolt Length

The clearest difference is price: Bolt Length at Free against Gengou's $0.99. Gengou's advantage is rating (3.8 vs 3.0) and in-app purchases (none vs 1). On ratings volume, update cadence, device support and iOS requirement there is nothing between them.

Bolt Length is free to download; Gengou costs $0.99 up front. Bolt Length sells 1 one-off in-app purchase. Gengou asks for nothing beyond the download.

Gengou holds the better App Store score, 3.8 against 3.0. Both are backed by a comparable volume of ratings — 4 and 2 respectively. Written reviews point the same way: 66% of Gengou's written reviews are positive against 33% of Bolt Length's.

Gengou ships an update every 30 months, Bolt Length every 20 months. The most recent releases landed on October 31, 2026 and November 1, 2026 respectively.

## The numbers

| Metric | Gengou | Bolt Length |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | **[3.8 (4 ratings)](https://appshunter.io/ios/app/gengou/id288968943/reviews)** | [3.0 (2 ratings)](https://appshunter.io/ios/app/bolt-length-nominal-length/id1042345193/reviews) |
| Number of ratings | **4** | 2 |
| Positive reviews | **66.1% of reviews** | 33.3% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 30 months | **Every 20 months** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 3 MB | 6 MB |
| Requires iOS | 15.0 | **14.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Masayuki Akamatsu](https://appshunter.io/developer/284722836) | [mitsunori oishi](https://appshunter.io/developer/905649994) |

## What reviewers say

### Gengou

[App page](https://appshunter.io/ios/app/gengou/id288968943)

Quickly convert between Japanese era names and Christian era years. Features include era and year searches, period and era pickers, and the ability to display text in Japanese or English.

**Highlights:** Era and Year Search, Period Picker, Era Picker, Christian Era Year Picker, Japanese Era Year Picker, Show This Year Button, Dual Language Support (JP/EN)

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

**In-app purchases:** none


### Bolt Length

[App page](https://appshunter.io/ios/app/bolt-length-nominal-length/id1042345193)

This application helps calculate the length of metric coarse screws based on Japanese Industrial Standards. It is designed for mechanical design purposes and should be used at the user's own risk.

**Highlights:** Metric coarse screw length calculation, Conforms to Japanese Industrial Standards (JIS), Designed for mechanical design, User risk disclaimer

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Hide Ads | $1.99 | one-time |


## Frequently asked questions

### Is Gengou free?

Gengou costs $0.99, with no in-app purchases.

### Is Bolt Length free?

Bolt Length is free to download, with in-app purchases available.

### Which has better reviews, Gengou or Bolt Length?

Gengou is rated higher. Gengou averages 3.8 out of 5 from 4 ratings, while Bolt Length averages 3.0 from 2 ratings.

### Do Gengou or Bolt Length have ads?

Bolt Length shows ads; Gengou does not.

### Which is updated more often, Gengou or Bolt Length?

Gengou ships an update every 30 months, and Bolt Length every 20 months. Most recently, Gengou was updated on October 31, 2026 and Bolt Length on November 1, 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.*