Comparison

RPN Calc vs iCrucible

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

Head to head
About

RPN Calc

This app provides a straightforward reverse Polish notation (RPN) calculator experience, inspired by classic HP models. It offers a clean interface with large buttons for quick calculations on iPhone, iPad, and Apple Watch, along with a convenient Today Extension for immediate access.

Highlights
  • Reverse Polish Notation (RPN) input
  • Clean, simple interface
  • Large, easy-to-press buttons
  • iPhone, iPad, and Apple Watch support
  • Today Extension for quick access
Features
Read full description

A simple reverse polish notation calculator loosely based on my trusty HP-32SII that runs on iPhone, iPad, and Apple Watch! If you are familiar with HP RPN calculators, the operation of this calculator should seem very straightforward - albeit simplified. It can't be programmed, and it doesn't handle binary, or hexadecimal numbers. But, it has a clean, simple interface with large, easy to press buttons. It has all of the functions required for quick calculations when your iPhone is handier than your computer or calculator. And, remember those cool calculator watches from the 1980s? Unfortunately, none of them were RPN. RPN Calc brings a reverse polish notation watch calculator to the Apple Watch! In addition to the standard RPN Calculator app that runs on iPhone, iPad, and Apple Watch, RPN Calc includes a handy micro RPN Calc Today Extension available for convenient access to quick calculations from the pull down Today screen.

About

iCrucible

Read full description

iCrucible is an AI tool for Materials Science. Using this app, you can learn about how AI tools work for materials screening, and may discover candidate compounds. Learn more at our website: https://www.rimcs.co.jp/ iCrucible makes a prediction of a ternary system on your iPhone or iPad without external services, using graph neural networks and crystal prototype databases bundled in the app. You can watch the phase diagram redrawn at the end of each stage during performing the prediction task. Note that it is the phase diagram at absolute zero (i.e., 0 kelvin) and around zero pressure (i.e., 0 kilobar). Performance It takes a few seconds to minutes depending on the creation settings and your device. The app has a multithreading option to accelerate the core of the AI tool - for example, computationally intensive tasks are sped up around 2.5x on M1 iPad Air. Chemical System A chemical system is selected by choosing three unique chemical elements from: • Element List (with group and period restriction) or • Periodic Table Materials Screening The materials screening is conducted by thresholding two values: • Predicative Variance • Stability (Energy above Convex Hull) Phase Diagram Drawing The drawing is customizable and responsive with useful features: • Formula Labeling • Stability Thresholding • Zoom • Mark Size • Font Size • Balloon with each compound information Confidence Chart The chart shows the distribution of predicative confidences, and provides an overall confidence of the system prediction and the phase diagram. Compound Table The table shows stable and metastable compounds with stabilities and predicative confidences, from which you can easily choose candidate compounds. Settings You can set the default preferences of the chemical system creation and the phase diagram drawing in the App's Settings. The entrance of the In-App Shop is also located in the App's Settings. We offer Free, Standard, and Premium plan. You can subscribe to one of Standard and Premium plan at the In-App Shop. The Shop's Help describes the system tiers used for the content management. Free features: • Free Elements: H to Ar. (*) • Ensemble Size: M = 1. • Prototype Database: Small only. • You can take a note about each chemical system to not forget any novel findings and great ideas. Standard features: • Standard Elements: K to Xe. (*) • Ensemble Size: M is not more than 5. • Prototype Database: Small, Medium, and Large. • You can sort chemical systems into Stocks that are a storage for them. • Chemical systems can be shared between your devices by peer-to-peer Wi-Fi networking. Premium features: • Premium Elements: Cs to Pu except Po to Ra. (*) • Ensemble Size: M is not more than 10. • Prototype Database: all scales, that is, Small, Medium, Large, and Huge. • Multithreading can be used to accelerate the core of the AI tool - for example, computationally intensive tasks are sped up around 2.5x on M1 iPad Air. * Noble gas elements are not available. Flame Gems You need flame gems for a non-free system creation, and can buy them at the In-App Shop. The Shop's Help describes how to consume flame gems and has the cost calculator. You have to buy no flame gems if you are on the Free plan. Terms of Use: http://www.apple.com/legal/itunes/appstore/dev/stdeula

Screenshots

RPN Calc3 screens
iCrucible4 screens

Verdict

The call

The clearest difference is price: iCrucible at Free against RPN Calc's $0.99. RPN Calc's advantage is in-app purchases (none vs 8). On update cadence, ads, 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

iCrucible is free to download; RPN Calc costs $0.99 up front. iCrucible sells 8 in-app purchases, starting at $2.99 per month. RPN Calc asks for nothing beyond the download.

UpkeepUpdate frequency

RPN Calc ships an update every 3 months, iCrucible every 5 months. The most recent releases landed on October 24, 2026 and October 27, 2026 respectively.

Scorecard2 real differences · 8 level
RPN Calc versus iCrucible: the parameters behind the verdict, then further details
ParameterRPN CalciCrucible
Price$0.99Free — better
Rating4.0 (6 ratings) — better—
Positive reviews37.9% of reviews—
Number of ratings6 — better—
Update frequencyEvery 3 months — betterEvery 5 months
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree—
DevicesiPhone, iPad, Apple Watch — betteriPhone, iPad
Requires iOS16.0 — better17.2
Further details — not scored
Size3 MB172 MB
Age rating+44+
DeveloperJames MattisRIMCS LLC

In-app purchases

None

RPN Calc

No in-app purchases

8 purchases

iCrucible

Subscriptions4
  • Standard$2.991 Month
  • Premium3 Days trial$4.991 Month
  • Standard$29.991 Year
Show 1 more
  • Premium$49.991 Year
One-time4
  • 500 Flame Gems$4.99
  • 2,500 Flame Gems$23.99
  • 5,000 Flame Gems$46.99
Show 1 more
  • 10,000 Flame Gems$91.90

Questions

Is RPN Calc free?
RPN Calc costs $0.99, with no in-app purchases.
Is iCrucible free?
iCrucible is free to download, with in-app purchases available.
Do RPN Calc or iCrucible have ads?
Neither RPN Calc nor iCrucible shows ads.
Which is updated more often, RPN Calc or iCrucible?
RPN Calc ships an update every 3 months, and iCrucible every 5 months. Most recently, RPN Calc was updated on October 24, 2026 and iCrucible on October 27, 2026.

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