# s＊単位変換 vs 19×19 暗算脳トレ

The clearest difference is ads: s＊単位変換 at none against 19×19 暗算脳トレ's shown. s＊単位変換 also leads on update cadence (every 2 days vs every 9 days). 19×19 暗算脳トレ's advantage is iOS requirement (13.0 vs 18.6). On price, 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.

s＊単位変換 ships an update every 2 days, 19×19 暗算脳トレ every 9 days. The most recent releases landed on October 25, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | s＊単位変換 | 19×19 暗算脳トレ |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | No | No |
| Ads | **No** | Yes |
| Update frequency | **Every 2 days** | Every 9 days |
| Size | 1 MB | 38 MB |
| Requires iOS | 18.6 | **13.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Seigo Mizouchi](https://appshunter.io/developer/1880010064) | [Atsushi Isai](https://appshunter.io/developer/1881655484) |

## What reviewers say

### s＊単位変換

[App page](https://appshunter.io/ios/app/s/id6759642495)

**Features:** macOS Compatibility

**In-app purchases:** none


### 19×19 暗算脳トレ

[App page](https://appshunter.io/ios/app/1919/id6763848289)

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

**In-app purchases:** none


## Frequently asked questions

### Is s＊単位変換 free?

s＊単位変換 is free to download, with no in-app purchases.

### Is 19×19 暗算脳トレ free?

19×19 暗算脳トレ is free to download, with no in-app purchases.

### Do s＊単位変換 or 19×19 暗算脳トレ have ads?

19×19 暗算脳トレ shows ads; s＊単位変換 does not.

### Which is updated more often, s＊単位変換 or 19×19 暗算脳トレ?

s＊単位変換 ships an update every 2 days, and 19×19 暗算脳トレ every 9 days. Most recently, s＊単位変換 was updated on October 25, 2026 and 19×19 暗算脳トレ on October 28, 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.*