# OTenkeyCalc vs CalcKing Pro

The clearest difference is in-app purchases: OTenkeyCalc at none against CalcKing Pro's 1. CalcKing Pro's advantage is ads (none vs shown). On price, update cadence, device support and iOS requirement there is nothing between them.

Both are free to download. CalcKing Pro sells 1 one-off in-app purchase. OTenkeyCalc asks for nothing beyond the download.

OTenkeyCalc ships an update every 2 weeks, CalcKing Pro weekly. The most recent releases landed on October 27, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | OTenkeyCalc | CalcKing Pro |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | Yes | **No** |
| Update frequency | Every 2 weeks | **Weekly** |
| Size | 37 MB | 2 MB |
| Requires iOS | 16.7.10 | **15.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Hideaki Uchikoshi](https://appshunter.io/developer/1559575002) | [文娟 唐](https://appshunter.io/developer/1870722016) |

## What reviewers say

### OTenkeyCalc

[App page](https://appshunter.io/ios/app/otenkeycalc/id6502439720)

**Features:** macOS Compatibility

**In-app purchases:** none


### CalcKing Pro

[App page](https://appshunter.io/ios/app/calcking-pro-professional/id6758431895)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 解锁功能 | $3.99 | one-time |


## Frequently asked questions

### Is OTenkeyCalc free?

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

### Is CalcKing Pro free?

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

### Do OTenkeyCalc or CalcKing Pro have ads?

OTenkeyCalc shows ads; CalcKing Pro does not.

### Which is updated more often, OTenkeyCalc or CalcKing Pro?

OTenkeyCalc ships an update every 2 weeks, and CalcKing Pro weekly. Most recently, OTenkeyCalc was updated on October 27, 2026 and CalcKing Pro on October 25, 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.*