# Only One Calculator vs Conv3rtify

The clearest difference is in-app purchases: Only One Calculator at none against Conv3rtify's 1. Only One Calculator also leads on update cadence (every 2 weeks vs every 26 months) and iOS requirement (11.0 vs 15.1). On price, ads and device support there is nothing between them.

Both are free to download. Conv3rtify sells 1 one-off in-app purchase. Only One Calculator asks for nothing beyond the download.

Only One Calculator ships an update every 2 weeks, Conv3rtify every 26 months. The most recent releases landed on November 3, 2026 and November 7, 2026 respectively.

## The numbers

| Metric | Only One Calculator | Conv3rtify |
| --- | --- | --- |
| 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** | Yes |
| Ads | No | No |
| Update frequency | **Every 2 weeks** | Every 26 months |
| Monetization | Free | — |
| Size | 34 MB | 40 MB |
| Requires iOS | **11.0** | 15.1 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Jia Hua Huang](https://appshunter.io/developer/1488596496) | [Ilya Emeliyanov](https://appshunter.io/developer/1602343908) |

## 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


### Conv3rtify

[App page](https://appshunter.io/ios/app/conv3rtify/id1602343906)

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Conv3rtify+ | $2.99 | one-time |


## Frequently asked questions

### Is Only One Calculator free?

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

### Is Conv3rtify free?

Conv3rtify is free to download, with in-app purchases available.

### Do Only One Calculator or Conv3rtify have ads?

Neither Only One Calculator nor Conv3rtify shows ads.

### Which is updated more often, Only One Calculator or Conv3rtify?

Only One Calculator ships an update every 2 weeks, and Conv3rtify every 26 months. Most recently, Only One Calculator was updated on November 3, 2026 and Conv3rtify on November 7, 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.*