# Cost Index vs ChatModel

The clearest difference is in-app purchases: Cost Index at none against ChatModel's 3. Cost Index also leads on iOS requirement (8.0 vs 14.0). ChatModel's advantage is update cadence (monthly vs every 16 months). On price, ads and device support there is nothing between them.

Both are free to download. ChatModel sells 3 in-app purchases, starting at $3.99 per 7 days. Cost Index asks for nothing beyond the download.

Cost Index ships an update every 16 months, ChatModel monthly. The most recent releases landed on October 6, 2026 and October 11, 2026 respectively.

## The numbers

| Metric | Cost Index | ChatModel |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/cost-index/id671845599/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 16 months | **Monthly** |
| Monetization | Free | — |
| Size | 3 MB | 15 MB |
| Requires iOS | **8.0** | 14.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 9+ |
| Developer | [Flight Efficiency Limited](https://appshunter.io/developer/466443228) | [Qijie Information](https://appshunter.io/developer/1717060398) |

## What reviewers say

### Cost Index

[App page](https://appshunter.io/ios/app/cost-index/id671845599)

This app helps airline and corporate aircraft operators achieve significant operational savings by calculating the optimum cruise speed for flights based on pilot-inputted conditions and aircraft-specific data. It offers advanced features for cost, fuel, and time optimization, including level change analysis and turbulence margin adjustments.

**Highlights:** Optimum cruise speed calculation, Customizable operational data display, Minimum fuel burn speed for long range, Turbulence margin adjustment, Level change analysis for climb/descent decisions, Automated data updates

**Features:** macOS Compatibility

**In-app purchases:** none


### ChatModel

[App page](https://appshunter.io/ios/app/chatmodel-multiple-models/id6479516706)

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weekly Plus | $3.99 | per 7 days |
| Monthly Plus | $12.99 | per month |
| Annual Plus | $119.00 | per year |


## Frequently asked questions

### Is Cost Index free?

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

### Is ChatModel free?

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

### Do Cost Index or ChatModel have ads?

Neither Cost Index nor ChatModel shows ads.

### Which is updated more often, Cost Index or ChatModel?

Cost Index ships an update every 16 months, and ChatModel monthly. Most recently, Cost Index was updated on October 6, 2026 and ChatModel on October 11, 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.*