# Concentrations vs Unit Converter....

The clearest difference is in-app purchases: Concentrations at none against Unit Converter....'s 2. Concentrations also leads on ads (none vs shown). Unit Converter....'s advantage is update cadence (every 2 weeks vs every 3 months) and device support (3 vs 1). On price there is nothing between them.

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

Concentrations ships an update every 3 months, Unit Converter.... every 2 weeks. The most recent releases landed on September 13, 2026 and September 17, 2026 respectively.

## The numbers

| Metric | Concentrations | Unit Converter.... |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 3 months | **Every 2 weeks** |
| Size | 7 MB | 106 MB |
| Requires iOS | 18.5 | **13.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Marcal Casas Cartagena](https://appshunter.io/developer/468150889) | [Olga Ivanova](https://appshunter.io/developer/1733570435) |

## What reviewers say

### Concentrations

[App page](https://appshunter.io/ios/app/concentrations/id468150886)

**In-app purchases:** none


### 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 |


## Frequently asked questions

### Is Concentrations free?

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

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

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

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

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

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

Concentrations ships an update every 3 months, and Unit Converter.... every 2 weeks. Most recently, Concentrations was updated on September 13, 2026 and Unit Converter.... on September 17, 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.*