OTenkeyCalc vs CalcKing Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
OTenkeyCalc
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Numeric ten keypad calculator that also displays the current temperature and weather at your current location * Weather information source: Apple Weather Service https://developer.apple.com/weatherkit/data-source-attribution/ https://support.apple.com/ja-jp/105038
CalcKing Pro
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Professional engineering calculator, the mobile computing tool for engineers! No ad interference: Specifically designed for engineers, with a pure usage experience and no pop-up ads. Full coverage of core functions: Basic scientific calculations: Trigonometric functions, logarithms and exponents, power operations, constant calls (π/e, etc.), support for degree/radian conversion, meeting general calculation needs. 12 types of unit conversions: Length, weight, area, volume, temperature, speed, etc., covering meters/cm/inches, kilograms/pounds, etc. Common sub-units, one-click quick conversion. Base conversion: Supports binary, octal, decimal, and hexadecimal conversions, suitable for electronic/computer engineering scenarios. Specialized engineering calculations: Built-in mechanics, circuits, materials, etc. Modules, solving professional problems such as force on inclined planes, series resistors, etc. User-friendly design: Portrait operation: Compatible with iPhone, using the vertical screen in engineering scenarios is more convenient. Local saved calculation history: Automatically records the last 20 calculations, not lost when uninstalling, and can be recalled at any time. Precise adaptation: Optimized for on-site work by engineers, clear display of large numbers, real-time input verification to avoid errors. Efficient work, time and effort-saving: From basic formulas to complex engineering problems, all are covered, helping you focus on core work!
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | OTenkeyCalc | CalcKing Pro |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 2 weeks | Weekly — better |
| Ads | Yes | No — better |
| In-app purchases | No — better | Yes |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 16.7.10 | 15.0 — better |
| Further details — not scored | ||
| Size | 37 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Hideaki Uchikoshi | 文娟 唐 |
In-app purchases
OTenkeyCalc
No in-app purchases
CalcKing Pro
- 解锁功能$3.99









