# Duncan Drill Calibration vs FireFly

The clearest difference is in-app purchases: Duncan Drill Calibration at none against FireFly's 1. Duncan Drill Calibration also leads on iOS requirement (15.1 vs 18). FireFly's advantage is update cadence (every 3 months vs every 8 months). On price, ads and device support there is nothing between them.

Both are free to download. FireFly sells 1 in-app purchase, starting at $14.99 per year. Duncan Drill Calibration asks for nothing beyond the download.

Duncan Drill Calibration ships an update every 8 months, FireFly every 3 months. The most recent releases landed on October 27, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | Duncan Drill Calibration | FireFly |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 8 months | **Every 3 months** |
| Size | 34 MB | 18 MB |
| Requires iOS | **15.1** | 18 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Giltrap Engineering Ltd](https://appshunter.io/developer/1593495399) | [Dylan Haycraft](https://appshunter.io/developer/1855182957) |

## What reviewers say

### Duncan Drill Calibration

[App page](https://appshunter.io/ios/app/duncan-drill-calibration/id6444295647)

**Features:** macOS Compatibility

**In-app purchases:** none


### FireFly

[App page](https://appshunter.io/ios/app/firefly-flight-log/id6755642320)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Yearly | $14.99 | per year |


## Frequently asked questions

### Is Duncan Drill Calibration free?

Duncan Drill Calibration is free to download, with no in-app purchases.

### Is FireFly free?

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

### Do Duncan Drill Calibration or FireFly have ads?

Neither Duncan Drill Calibration nor FireFly shows ads.

### Which is updated more often, Duncan Drill Calibration or FireFly?

Duncan Drill Calibration ships an update every 8 months, and FireFly every 3 months. Most recently, Duncan Drill Calibration was updated on October 27, 2026 and FireFly on October 20, 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.*