# Uncertainty Calculator vs IELTS Collocation PRO

The clearest difference is in-app purchases: Uncertainty Calculator at none against IELTS Collocation PRO's 1. Uncertainty Calculator also leads on price ($3.99 vs $8.99) and rating (5.0 vs 4.8). IELTS Collocation PRO's advantage is ratings volume (662 vs 1) and iOS requirement (10.3 vs 17.0). On update cadence, ads and device support there is nothing between them.

Uncertainty Calculator costs $3.99 and IELTS Collocation PRO $8.99 up front. IELTS Collocation PRO sells 1 one-off in-app purchase. Uncertainty Calculator asks for nothing beyond the download.

Uncertainty Calculator holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: IELTS Collocation PRO has 662 ratings behind it against 1, so its average is the more settled of the two.

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on October 2, 2026 and October 16, 2026 respectively.

## The numbers

| Metric | Uncertainty Calculator | IELTS Collocation PRO |
| --- | --- | --- |
| Price | **$3.99** | $8.99 |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/uncertainty-calculator/id1170905440/reviews)** | [4.8 (662 ratings)](https://appshunter.io/ios/app/ielts-collocation-pro/id1422950549/reviews) |
| Number of ratings | 1 | **662** |
| Positive reviews | — | 80.8% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 1 MB | 185 MB |
| Requires iOS | 17.0 | **10.3** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Roman Volinsky](https://appshunter.io/developer/977951850) | [Nguyen Thi Hoai Thu](https://appshunter.io/developer/1321248741) |

## What reviewers say

### Uncertainty Calculator

[App page](https://appshunter.io/ios/app/uncertainty-calculator/id1170905440)

This app allows users to perform error propagation calculations for mathematical expressions involving uncertain variables. It supports absolute and relative error inputs, various functions, and trigonometric calculations in degrees or radians. The tool helps ensure accurate reporting of results based on estimated errors.

**Highlights:** Error propagation calculations, Absolute and relative error input, Support for mathematical functions, Trigonometric calculations (degrees/radians), Variable combination in expressions, Significant figure guidance

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

**In-app purchases:** none


### IELTS Collocation PRO

[App page](https://appshunter.io/ios/app/ielts-collocation-pro/id1422950549)

Enhance your English vocabulary for IELTS exams by learning essential word pairings. This app focuses on collocations, which are crucial for achieving higher scores in both writing and speaking sections.

**Highlights:** Learn essential IELTS collocations, Improve writing vocabulary, Boost speaking fluency, Offline access, Understand collocation patterns, Practice with example sentences

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium version | $8.99 | one-time |

**What reviewers like**

- 👍 Easy to use and user-friendly interface
- 📚 Comprehensive vocabulary learning resource
- 🎯 Excellent for IELTS exam preparation
- 💡 Well-organized and efficient structure
- 🆓 Generous free version available

**What reviewers complain about**

- 🐛 Radio feature not working
- 💰 Premium version lacks differentiation from free version
- 🌐 Requires internet connection to function
- ❌ Missing collocation data for many words
- 🔧 Premium purchase issues with latest updates

**Reported bugs**

- Radio feature not operational
- App non-functional without internet connection
- Premium version not recognized after update
- Ads continue to display for premium users
- Study Centre doesn't show correct answers for wrong responses

**Requested features**

- Alphabetical categorization of words
- Word count numbering system
- Collocation examples for search terms
- Offline functionality
- Ability to delete recent search history


## Frequently asked questions

### Is Uncertainty Calculator free?

Uncertainty Calculator costs $3.99, with no in-app purchases.

### Is IELTS Collocation PRO free?

IELTS Collocation PRO costs $8.99, and also offers in-app purchases.

### Which has better reviews, Uncertainty Calculator or IELTS Collocation PRO?

Uncertainty Calculator is rated higher. Uncertainty Calculator averages 5.0 out of 5 from 1 ratings, while IELTS Collocation PRO averages 4.8 from 662 ratings.

### Do Uncertainty Calculator or IELTS Collocation PRO have ads?

Neither Uncertainty Calculator nor IELTS Collocation PRO shows ads.

### Which is updated more often, Uncertainty Calculator or IELTS Collocation PRO?

Uncertainty Calculator ships an update every 3 months, and IELTS Collocation PRO every 3 months. Most recently, Uncertainty Calculator was updated on October 2, 2026 and IELTS Collocation PRO on October 16, 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.*