# Only One Calculator vs Key Calculator

Only One Calculator and Key Calculator are too close to call on the numbers: across 5 compared parameters — price, ads, in-app purchases and device support among them — neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

## The numbers

| Metric | Only One Calculator | Key Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/only-one-calculator/id1488596497/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 2 weeks | — |
| Monetization | Free | — |
| Size | 34 MB | 27 MB |
| Requires iOS | **11.0** | 12.0 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Jia Hua Huang](https://appshunter.io/developer/1488596496) | [瑞勤 李](https://appshunter.io/developer/1401713785) |

## What reviewers say

### Only One Calculator

[App page](https://appshunter.io/ios/app/only-one-calculator/id1488596497)

This utility app offers instant currency exchange and unit conversions, making it ideal for travel and shopping. It features undo/redo functionality for easy editing and supports over 160 currencies with customizable update frequencies.  Users can also access calculation history and customize the keyboard.

**Highlights:** Instant currency exchange, Unit conversion (length, weight, area, volume, temperature), Undo/Redo functionality, History of calculations, Customizable keyboard layout, Real-time calculation results

**In-app purchases:** none


### Key Calculator

[App page](https://appshunter.io/ios/app/key-calculator/id6740821637)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Only One Calculator free?

Only One Calculator is free to download, with no in-app purchases.

### Is Key Calculator free?

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

### Do Only One Calculator or Key Calculator have ads?

Neither Only One Calculator nor Key Calculator shows ads.

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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.*