Comparison

OTenkeyCalc vs CalcKing Pro

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

OTenkeyCalc

Features
Read full description

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

About

CalcKing Pro

Features
Read full description

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

OTenkeyCalc1 screens
CalcKing Pro4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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

UpkeepUpdate frequency

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

Scorecard2 real differences · 4 level
OTenkeyCalc versus CalcKing Pro: the parameters behind the verdict, then further details
ParameterOTenkeyCalcCalcKing Pro
PriceFreeFree
Update frequencyEvery 2 weeksWeekly — better
AdsYesNo — better
In-app purchasesNo — betterYes
DevicesiPhone, iPadiPhone, iPod
Requires iOS16.7.1015.0 — better
Further details — not scored
Size37 MB2 MB
Age rating4+4+
DeveloperHideaki Uchikoshi文娟 唐

In-app purchases

None

OTenkeyCalc

No in-app purchases

1 purchases

CalcKing Pro

One-time1
  • 解锁功能$3.99

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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