# Unit Converter.... vs Chemicastle

The clearest difference is in-app purchases: Chemicastle at none against Unit Converter....'s 2. Chemicastle also leads on ads (none vs shown). Unit Converter....'s advantage is update cadence (every 2 weeks vs every 4 months) and iOS requirement (13.0 vs 15.0). On price and device support there is nothing between them.

Both are free to download. Unit Converter.... sells 2 in-app purchases, starting at $1.99 per month. Chemicastle asks for nothing beyond the download.

Unit Converter.... ships an update every 2 weeks, Chemicastle every 4 months. The most recent releases landed on October 21, 2026 and October 24, 2026 respectively.

## The numbers

| Metric | Unit Converter.... | Chemicastle |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | **Every 2 weeks** | Every 4 months |
| Size | 106 MB | 301 MB |
| Requires iOS | **13.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 9+ |
| Developer | [Olga Ivanova](https://appshunter.io/developer/1733570435) | [Haute ecole pedagogique HEP-BEJUNE](https://appshunter.io/developer/1835648343) |

## What reviewers say

### Unit Converter....

[App page](https://appshunter.io/ios/app/unit-converter/id6751115020)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| units_by_oliva_subscription | $1.99 | per month |
| units_by_oliva_donation | $1.99 | one-time |


### Chemicastle

[App page](https://appshunter.io/ios/app/chemicastle/id6753705536)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Unit Converter.... free?

Unit Converter.... is free to download, with in-app purchases available.

### Is Chemicastle free?

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

### Do Unit Converter.... or Chemicastle have ads?

Unit Converter.... shows ads; Chemicastle does not.

### Which is updated more often, Unit Converter.... or Chemicastle?

Unit Converter.... ships an update every 2 weeks, and Chemicastle every 4 months. Most recently, Unit Converter.... was updated on October 21, 2026 and Chemicastle on October 24, 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.*