# O vs Mechanical Engg. Calculator

The clearest difference is review sentiment: O at 100% against Mechanical Engg. Calculator's 25%. O also leads on rating (5.0 vs 3.7). Mechanical Engg. Calculator's advantage is device support (3 vs 1) and ratings volume (3 vs 1). On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

O holds the better App Store score, 5.0 against 3.7. Both are backed by a comparable volume of ratings — 1 and 3 respectively. Written reviews point the same way: 100% of O's written reviews are positive against 25% of Mechanical Engg. Calculator's.

O ships an update every 11 months, Mechanical Engg. Calculator every 21 months. Both last shipped on November 2, 2026.

## The numbers

| Metric | O | Mechanical Engg. Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/o-ring-master/id1072051820/reviews)** | [3.7 (3 ratings)](https://appshunter.io/ios/app/mechanical-engg-calculator/id1100129593/reviews) |
| Number of ratings | 1 | **3** |
| Positive reviews | **100.0% of reviews** | 25.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 11 months** | Every 21 months |
| Monetization | Free | Free |
| Size | 47 MB | 24 MB |
| Requires iOS | 16.0 | **13.0** |
| Devices | iPhone | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [GE MAO RUBBER INDUSTRIAL CO., LTD.](https://appshunter.io/developer/1078558543) | [Trelleborg Sealing Solutions](https://appshunter.io/developer/396863758) |

## What reviewers say

### O

[App page](https://appshunter.io/ios/app/o-ring-master/id1072051820)

This app provides a comprehensive offline tool for selecting standard rubber seal sizes, including O-Rings, X-Rings, and Back-Up Rings. It offers dimension searches, housing calculations for various sealing applications, and supports multiple international standards in both metric and imperial units.

**Highlights:** Offline standard rubber seal size selection, Search for O-Ring, X-Ring, and Back-Up Ring sizes, O-Ring housing calculations for sealing applications, Supports multiple international standards (AS568, METRIC, JIS, etc.), Metric and Imperial unit support, Substitutable O-Ring size suggestions

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

**In-app purchases:** none


### Mechanical Engg. Calculator

[App page](https://appshunter.io/ios/app/mechanical-engg-calculator/id1100129593)

This app provides a comprehensive collection of ~250 formulas across 16 categories for mechanical engineering, physics, and mathematics. Users can easily perform calculations by selecting a formula and inputting variables.

**Highlights:** ~250 formulas, 16 categories, Mathematics, physics, mechanical engineering, User-friendly calculation input, Customizable for convenience

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is O free?

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

### Is Mechanical Engg. Calculator free?

Mechanical Engg. Calculator is free to download, with no in-app purchases.

### Which has better reviews, O or Mechanical Engg. Calculator?

O is rated higher. O averages 5.0 out of 5 from 1 ratings, while Mechanical Engg. Calculator averages 3.7 from 3 ratings.

### Do O or Mechanical Engg. Calculator have ads?

Neither O nor Mechanical Engg. Calculator shows ads.

### Which is updated more often, O or Mechanical Engg. Calculator?

O ships an update every 11 months, and Mechanical Engg. Calculator every 21 months. Most recently, O was updated on November 2, 2026 and Mechanical Engg. Calculator on November 2, 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.*