# Multiplier vs Primal's 3D Knee

The clearest difference is in-app purchases: Multiplier at none against Primal's 3D Knee's 1. Multiplier also leads on iOS requirement (13.0 vs 15.0). Primal's 3D Knee's advantage is update cadence (every 2 months vs every 7 months). On price, ads and device support there is nothing between them.

Both are free to download. Primal's 3D Knee sells 1 one-off in-app purchase. Multiplier asks for nothing beyond the download.

Multiplier ships an update every 7 months, Primal's 3D Knee every 2 months. The most recent releases landed on July 2, 2026 and September 10, 2026 respectively.

## The numbers

| Metric | Multiplier | Primal's 3D Knee |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (24 ratings)](https://appshunter.io/ios/app/multiplier/id460335161/reviews)** | — |
| Number of ratings | **24** | — |
| Positive reviews | 83.3% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 7 months | **Every 2 months** |
| Monetization | Paid | — |
| Size | 62 MB | 125 MB |
| Requires iOS | **13.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 12+ | 12+ |
| Developer | [LifeBridge Health](https://appshunter.io/developer/460335164) | [Pharma Intelligence UK Ltd](https://appshunter.io/developer/1678054030) |

## What reviewers say

### Multiplier

[App page](https://appshunter.io/ios/app/multiplier/id460335161)

This app automates complex calculations for predicting mature height, bone length, and limb length discrepancies in children. It simplifies manual methods, reducing calculation time and errors for various orthopedic and growth-related assessments.

**Highlights:** Predict mature height, Calculate bone length, Assess limb length discrepancy, Analyze growth remaining, Plot height on CDC charts, Scanogram calculations, Foot length analysis

**Features:** macOS Compatibility

**In-app purchases:** none


### Primal's 3D Knee

[App page](https://appshunter.io/ios/app/primals-3d-knee/id1658547427)

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Primal's 3D Knee | $39.99 | one-time |


## Frequently asked questions

### Is Multiplier free?

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

### Is Primal's 3D Knee free?

Primal's 3D Knee is free to download, with in-app purchases available.

### Do Multiplier or Primal's 3D Knee have ads?

Neither Multiplier nor Primal's 3D Knee shows ads.

### Which is updated more often, Multiplier or Primal's 3D Knee?

Multiplier ships an update every 7 months, and Primal's 3D Knee every 2 months. Most recently, Multiplier was updated on July 2, 2026 and Primal's 3D Knee on September 10, 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.*