# RF Engineer's Calc vs Kestrel

The clearest difference is in-app purchases: RF Engineer's Calc at none against Kestrel's 4. Kestrel's advantage is update cadence (fortnightly vs every 10 months) and device support (3 vs 1). On price, ads and iOS requirement there is nothing between them.

Both are free to download. Kestrel sells 4 in-app purchases, starting at $3.99 per month. RF Engineer's Calc asks for nothing beyond the download.

RF Engineer's Calc ships an update every 10 months, Kestrel fortnightly. The most recent releases landed on October 6, 2026 and October 3, 2026 respectively.

## The numbers

| Metric | RF Engineer's Calc | Kestrel |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 10 months | **Fortnightly** |
| Size | 43 MB | 37 MB |
| Requires iOS | **16.1** | 17.0 |
| Devices | iPhone | **iPhone, iPad, Mac** |
| Age rating | 4+ | 4+ |
| Developer | [GRAHAM JOHN SMITH](https://appshunter.io/developer/1668396908) | [Michael Wright](https://appshunter.io/developer/1895416865) |

## What reviewers say

### RF Engineer's Calc

[App page](https://appshunter.io/ios/app/rf-engineers-calc/id1668396906)

**Features:** macOS Compatibility

**In-app purchases:** none


### Kestrel

[App page](https://appshunter.io/ios/app/kestrel-ssh-and-server-manager/id6764020106)

**Features:** Vision Pro support

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Kestrel Pro | $3.99 | per month |
| Kestrel Pro Yearly | $24.99 | per year |
| Kestrel Suite | $39.99 | per year |
| Kestrel Pro Lifetime | $50.00 | one-time |


## Frequently asked questions

### Is RF Engineer's Calc free?

RF Engineer's Calc is free to download, with no in-app purchases.

### Is Kestrel free?

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

### Do RF Engineer's Calc or Kestrel have ads?

Neither RF Engineer's Calc nor Kestrel shows ads.

### Which is updated more often, RF Engineer's Calc or Kestrel?

RF Engineer's Calc ships an update every 10 months, and Kestrel fortnightly. Most recently, RF Engineer's Calc was updated on October 6, 2026 and Kestrel on October 3, 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.*