# O vs Units Converter Pro

The clearest difference is in-app purchases: O at none against Units Converter Pro's 1. Units Converter Pro's advantage is update cadence (every 3 days vs every 18 months) and iOS requirement (9.3 vs 12.0). On price, ads and device support there is nothing between them.

Both are free to download. Units Converter Pro sells 1 one-off in-app purchase. O asks for nothing beyond the download.

O ships an update every 18 months, Units Converter Pro every 3 days. The most recent releases landed on October 19, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | O | Units Converter Pro |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.4 (5 ratings)](https://appshunter.io/ios/app/units-converter-pro/id1541377300/reviews)** |
| Number of ratings | — | **5** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 18 months | **Every 3 days** |
| Monetization | — | Free |
| Size | 16 MB | 11 MB |
| Requires iOS | 12.0 | **9.3** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [HUTCHINSON](https://appshunter.io/developer/862345826) | [Nixus Development](https://appshunter.io/developer/495677027) |

## What reviewers say

### O

[App page](https://appshunter.io/ios/app/o-ring-info/id1369062925)

**Features:** macOS Compatibility

**In-app purchases:** none


### Units Converter Pro

[App page](https://appshunter.io/ios/app/units-converter-pro/id1541377300)

Easily convert over 700 different units across various categories like length, area, currency, and temperature. This tool simplifies complex conversions for everyday use and professional needs.

**Highlights:** Converts 700+ units, Supports Angle, Area, Currency, Includes Data, Energy, Force, Covers Fuel, Length, Power, Handles Pressure, Speed, Temperature, Converts Time and Volume

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| remove ads | $1.99 | one-time |


## Frequently asked questions

### Is O free?

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

### Is Units Converter Pro free?

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

### Do O or Units Converter Pro have ads?

Neither O nor Units Converter Pro shows ads.

### Which is updated more often, O or Units Converter Pro?

O ships an update every 18 months, and Units Converter Pro every 3 days. Most recently, O was updated on October 19, 2026 and Units Converter Pro on October 20, 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.*