Gengou vs Bolt Length
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Gengou
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.
- 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)
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"Gengou" is a quick reference of the Japanese era system. This application has functions as below. - Era and Year Search - Period picker - Era picker - Christian era year picker - Japanese era year picker - Show this year button - Texts can be shown in Japanese or English independently of the default language setting. - Application badge can show this year number in the Japanese era or the Christian era. The Japanese era system identifies a year by the combination of the era name (Gengou or Nengou) and the year number within the era. For example, A.D. 2001 is Heisei 13. Please note that two Gengou schemes were used in Parallel from 1331 to 1392 during Nanboku-chō period. This application would be very useful if you are working with the governments, municipal offices and/or certain companies in Japan.
Bolt Length
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.
- Metric coarse screw length calculation
- Conforms to Japanese Industrial Standards (JIS)
- Designed for mechanical design
- User risk disclaimer
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This app is an application for calculating the length of the screw. ※:This app does not guarantee the effectiveness of the combination. ※:Use this application at your own risk. Conforms to the Japanese Industrial Standards (JIS). Screws are all metric coarse screw. For mechanical design. Sorry, Only in Japan.Because using the JIS.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | Gengou | Bolt Length |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 3.8 (4 ratings) — better | 3.0 (2 ratings) |
| Positive reviews | 66.1% of reviews — better | 33.3% of reviews |
| Number of ratings | 4 — better | 2 |
| Update frequency | Every 30 months | Every 20 months — better |
| Ads | No — better | Yes |
| In-app purchases | No — better | Yes |
| Monetization | Paid | Free with in-app purchases — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.0 | 14.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 6 MB |
| Age rating | 4+ | 4+ |
| Developer | Masayuki Akamatsu | mitsunori oishi |
Customer experience
Gengou
Bolt Length
In-app purchases
Gengou
No in-app purchases
Bolt Length
- Hide Ads$1.99
