# Duty vs AviCalc

The clearest difference is in-app purchases: AviCalc at none against Duty's 1. AviCalc also leads on iOS requirement (15.0 vs 17.6). Duty's advantage is update cadence (every 3 days vs every 3 weeks). On price, ads and device support there is nothing between them.

Both are free to download. Duty sells 1 in-app purchase, starting at $1.99 per year. AviCalc asks for nothing beyond the download.

Duty ships an update every 3 days, AviCalc every 3 weeks. The most recent releases landed on September 9, 2026 and September 19, 2026 respectively.

## The numbers

| Metric | Duty | AviCalc |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 days** | Every 3 weeks |
| Size | 44 MB | 9 MB |
| Requires iOS | 17.6 | **15.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Martin Handl](https://appshunter.io/developer/1202513077) | [Aldo Mendes Martins](https://appshunter.io/developer/377344895) |

## What reviewers say

### Duty

[App page](https://appshunter.io/ios/app/duty-rest/id6450999374)

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlimited access | $1.99 | per year |


### AviCalc

[App page](https://appshunter.io/ios/app/avicalc/id6474237308)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Duty free?

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

### Is AviCalc free?

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

### Do Duty or AviCalc have ads?

Neither Duty nor AviCalc shows ads.

### Which is updated more often, Duty or AviCalc?

Duty ships an update every 3 days, and AviCalc every 3 weeks. Most recently, Duty was updated on September 9, 2026 and AviCalc on September 19, 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.*