# Part66 vs Mechanical Formula

The clearest difference is review sentiment: Part66 at 60% against Mechanical Formula's 0%. Part66 also leads on update cadence (every 2 months vs every 4 months) and iOS requirement (10.3 vs 13.0). Mechanical Formula's advantage is rating (4.7 vs 4.5) and ratings volume (34 vs 10). On price, ads, in-app purchases and monetization model there is nothing between them.

Both are free to download. Part66 sells 11 one-off in-app purchases and Mechanical Formula sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

Mechanical Formula holds the better App Store score, 4.7 against 4.5. Both are backed by a comparable volume of ratings — 10 and 34 respectively. Written reviews complicate that: 60% of Part66's written reviews are positive against 0% of Mechanical Formula's, so the app with the better star average is not the one people write more warmly about.

Part66 ships an update every 2 months, Mechanical Formula every 4 months. The most recent releases landed on September 30, 2026 and October 6, 2026 respectively.

## The numbers

| Metric | Part66 | Mechanical Formula |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.5 (10 ratings)](https://appshunter.io/ios/app/part66-engineer/id889659306/reviews) | **[4.7 (34 ratings)](https://appshunter.io/ios/app/mechanical-formula/id1668948373/reviews)** |
| Number of ratings | 10 | **34** |
| Positive reviews | **60.0% of reviews** | 0.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 4 months |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Size | 38 MB | 42 MB |
| Requires iOS | **10.3** | 13.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [DAVID SOUTHERN](https://appshunter.io/developer/889659309) | [Kantaben Gorasiya](https://appshunter.io/developer/1640260396) |

## What reviewers say

### Part66

[App page](https://appshunter.io/ios/app/part66-engineer/id889659306)

Prepare for EASA Part 66 aircraft maintenance license exams with sample tests and flashcards. Generate unlimited random exams and analyze results to identify weak areas. Covers modules relevant to B1.1 and potentially FAA licenses.

**Highlights:** Sample exams for EASA Part 66 modules, Flashcards for purchased modules, Unlimited random exam generation, Exam timer with real-world time limits, Analysis of results and weak point identification, Email results for review

**Features:** macOS Compatibility

**In-app purchases (11)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Module 10 Exam 2 | $0.99 | one-time |
| module 10 Exam 3 | $0.99 | one-time |
| Module 15 Exam 2 | $0.99 | one-time |
| Module 7 Exam 2 | $0.99 | one-time |
| Module 8 Exam 2 | $0.99 | one-time |
| Module 8 Exam 3 | $0.99 | one-time |
| Module 8 Bank = 409 Questions. | $7.99 | one-time |
| Module 17 Full Bank = 614 Q | $8.99 | one-time |
| Module 10 Bank. 730 Questions. | $10.99 | one-time |
| Module 15 Full Bank = 1,129 Q | $11.99 | one-time |
| Module 7 Bank = 1,624 Question | $11.99 | one-time |


### Mechanical Formula

[App page](https://appshunter.io/ios/app/mechanical-formula/id1668948373)

This app provides over 200 essential mechanical engineering formulas and calculations in a user-friendly tool. It's designed to simplify complex concepts and speed up problem-solving for students, professionals, and educators.

**Highlights:** 200+ mechanical engineering formulas, Instant calculations, Intuitive interface, Real-world application explanations, Exam preparation aid, Lifetime Premium option

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime | $9.99 | one-time |


## Frequently asked questions

### Is Part66 free?

Part66 is free to download, with in-app purchases available.

### Is Mechanical Formula free?

Mechanical Formula is free to download, with in-app purchases available.

### Which has better reviews, Part66 or Mechanical Formula?

Mechanical Formula is rated higher. Part66 averages 4.5 out of 5 from 10 ratings, while Mechanical Formula averages 4.7 from 34 ratings.

### Do Part66 or Mechanical Formula have ads?

Neither Part66 nor Mechanical Formula shows ads.

### Which is updated more often, Part66 or Mechanical Formula?

Part66 ships an update every 2 months, and Mechanical Formula every 4 months. Most recently, Part66 was updated on September 30, 2026 and Mechanical Formula on October 6, 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.*