# AO Surgery Reference vs OrthoBMI

The clearest difference is price: AO Surgery Reference at Free against OrthoBMI's $0.99. AO Surgery Reference also leads on device support (3 vs 1) and iOS requirement (13.0 vs 26.2). OrthoBMI's advantage is rating (5.0 vs 4.4) and update cadence (every 5 days vs every 6 months). On ratings volume, ads and in-app purchases there is nothing between them.

AO Surgery Reference is free to download; OrthoBMI costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

OrthoBMI holds the better App Store score, 5.0 against 4.4. Both are backed by a comparable volume of ratings — 14 and 6 respectively. Written reviews point the same way: 86% of AO Surgery Reference's written reviews are positive against 100% of OrthoBMI's.

AO Surgery Reference ships an update every 6 months, OrthoBMI every 5 days. The most recent releases landed on October 23, 2026 and October 15, 2026 respectively.

## The numbers

| Metric | AO Surgery Reference | OrthoBMI |
| --- | --- | --- |
| Price | **Free** | $0.99 |
| Rating | [4.4 (14 ratings)](https://appshunter.io/ios/app/ao-surgery-reference/id403961165/reviews) | **[5.0 (6 ratings)](https://appshunter.io/ios/app/orthobmi-bmi-calculator/id6761197088/reviews)** |
| Number of ratings | **14** | 6 |
| Positive reviews | 85.8% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 5 days** |
| Monetization | **Free** | Paid |
| Size | 1 MB | 2 MB |
| Requires iOS | **13.0** | 26.2 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 17+ | 4+ |
| Developer | [AO Foundation](https://appshunter.io/developer/399757056) | [THOMAS WARD GILL JR](https://appshunter.io/developer/1888228854) |

## What reviewers say

### AO Surgery Reference

[App page](https://appshunter.io/ios/app/ao-surgery-reference/id403961165)

Access a comprehensive online repository of surgical knowledge for fracture management. It provides detailed guidance on diagnosis, treatment, and aftercare for numerous fracture types, supported by extensive illustrations and expert review.

**Highlights:** 353 fracture types covered, 172 surgical approaches, 1222 surgical procedures, Over 30,000 illustrations, Feline, canine, and equine fracture care, Powerful search function

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

**In-app purchases:** none


### OrthoBMI

[App page](https://appshunter.io/ios/app/orthobmi-bmi-calculator/id6761197088)

This medical tool calculates patient target weights for specific BMI thresholds, crucial for orthopedic surgery planning. It offers a fast, clinic-ready interface to determine BMI from actual weight or estimate weight needed to reach surgical BMI goals.

**Highlights:** BMI calculator for orthopedic and surgical use, Calculate target weight for BMI thresholds, Determine BMI from actual weight, Automatic outputs at BMI 35, 40, 45, and 50, Integrated BMI guidance for surgery, Optimized for iPhone and iPad

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is AO Surgery Reference free?

AO Surgery Reference is free to download, with no in-app purchases.

### Is OrthoBMI free?

OrthoBMI costs $0.99, with no in-app purchases.

### Which has better reviews, AO Surgery Reference or OrthoBMI?

OrthoBMI is rated higher. AO Surgery Reference averages 4.4 out of 5 from 14 ratings, while OrthoBMI averages 5.0 from 6 ratings.

### Do AO Surgery Reference or OrthoBMI have ads?

Neither AO Surgery Reference nor OrthoBMI shows ads.

### Which is updated more often, AO Surgery Reference or OrthoBMI?

AO Surgery Reference ships an update every 6 months, and OrthoBMI every 5 days. Most recently, AO Surgery Reference was updated on October 23, 2026 and OrthoBMI on October 15, 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.*