Comparison

i41CX+ vs RPN

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

Head to head
About

i41CX+

This advanced RPN scientific calculator offers workstation-class Computer Algebra System (CAS) capabilities, going beyond traditional replicas. It provides access to an extensive library of modules and programs, enhanced with iOS features, customizable skins, and iCloud support for seamless data management.

Highlights
  • RPN logic with 4-element stack
  • Extensive memory registers
  • Over 400 built-in functions
  • Computer Algebra System (CAS)
  • Virtual thermal printer/plotter
  • Access to HP-41 module library
  • Customizable skins and keyboard overlays
Features
Read full description

i41CX+ is an advanced programmable and expandable RPN scientific calculator with a virtual thermal printer/plotter and workstation-class CAS capabilities that is far beyond a mere replica of the original. In addition to being functionally equivalent to the world-renowned HP-41CX and providing access to its entire library of modules and programs, i41CX+ is enhanced with iOS and hardware features, keyboard overlays, rich set of import and export capabilities, traditional and upbeat diverse set of skins, complete color control, iCloud support, and much more. The i41CX+ CAS is a full implementation of REDUCE. It's like having Mathematica or the computational engine of Wolfram Alpha in your pocket and, best of all, it runs natively so no internet connection is required. The CAS is fully programmable and provides the ability to reuse previous results in computations. Moreover, the CAS has full access to the calculator registers so it is possible to combine RPN programs with CAS programs. This is the finest and most powerful scientific/engineering/financial calculator for iOS devices bar none. CALCULATOR FEATURES: • RPN logic with a 4 element deep memory stack • 319 main and 600 extended memory registers • Over 400 built-in functions, including over 100 functions created specifically for i41CX+ • Time, calendar, alarm, and stopwatch functions • Four module ports provide access to HP-41 expansion pacs • Rich set of functions and algorithms: numerical, mathematical, statistical, complex, matrix, numerical integration, curve fitting, solutions to equations, and much more • Powerful, flexible, and programmable Computer Algebra System (CAS) supporting symbolic, arbitrary precision, scalar, vector and matrix algebra calculations, 2D/3D plotting, and much more • Full-screen text editor with configurable font style and size, color scheme, a user configurable macro keyboard, and a numerical keyboard • Access to the entire HP-41 library of solutions for science, mathematics, statistics, engineering, business, financial, surveying, medicine, real estate, and many other domains • Programmable - virtually unlimited number of lines • User definable keyboard • Ability to operate the calculator using a Bluetooth keyboard • Device integration: external display mirroring, copy and paste, in-app mail, system keyboard, GPS, accelerometer, digital compass, time and date synchronization, AirPrint, and much more • Virtually unlimited data and program storage capacity using the device's flash memory for local storage • Import/export data, programs, overlays, modules, etc. via the web, email, and iTunes file sharing • iCloud syncing of files and preference settings • iOS 8 Notification Center widget • 43 available keyboard overlays and support for user created overlays • Sound support including synthetic tones and interface sounds • Support for calculator skins and optional mini stack display • Adjustable calculator speed, sound volume, and display colors • Usage & Examples table with usage tips and examples • Quick Reference Guide of all built-in functions • CAS Quick Reference with all built-in functions, operators, switches, and packages • Beautiful and clean user interface PRINTER FEATURES: • Support for printing, plotting, graphics, and special characters • User configurable and programmable print color • Export printer output via email, clipboard, or AirPrint • Ability to save a JPEG image of the paper roll to the device's photo album *********************************************************** A comprehensive FAQ and Mini-Manual are available at http://alsoftiphone.com/i41CXplus. Please don't hesitate to use the "Contact Us" link there if you cannot find the answers or information that you seek. Thank you.

About

RPN

Experience a faithful simulation of the groundbreaking HP-65 programmable calculator on your iPad. This app offers virtual program and data cards, a powerful card manager, and includes 170 original HP programs to get you started.

Highlights
  • Virtual program and data cards
  • Virtual paper tape printer
  • Database-driven card manager
  • Create, delete, label, and organize cards
  • Share via email, AirDrop, Dropbox, print
  • Paste and run existing HP-65 listings
  • Live display of stack and registers
  • Four operational modes including 'Super-65'
Features
Read full description

World's first pocket computer! Now running on your iPad. RPN-65 Pro is the first complete simulation of Hewlett-Packard's stunning HP-65 programmable calculator for iOS. Produced from 1974 to 1977 at an initial price of $795 (that's more close to $5,000 today!), the HP-65 was a breakthrough. Not only was it programmable, it also contained a motorized magnetic card reader - and still fit into Bill Hewlett's shirt pocket. Experience this revolutionary calculator on your iPad. With 170 original HP programs included with RPN-65 Pro, you can get started right away. "A work of art. Fantastic!" (MacBreak Weekly, episode 572) Features: • Virtual program and data cards • Virtual paper tape printer supports AirPrint • Powerful database-driven card manager • Create, delete, label, and organize a virtually unlimited number of cards • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • Paste existing HP-65 listings into RPN-65 and run them • "Live" display of stack, memory registers, program counter, flags • Reads data cards created by RPN-67 Pro and RPN-97 Pro • Supports external hardware keyboard Run RPN-65 Pro in any of 4 modes: 1 - Just like the original HP-65 2 - Same, but at high speed 3 - Includes user-interface improvements, like backstep key and jump to any program step 4 - "Super-65" with 999 program steps, 120 labels, 120 registers, nested subroutines, and much more For details, free program downloads, calculator handbook and much more, visit the RPN-65 website: cuveesoft.ch/rpn65

Screenshots

i41CX+4 screens

Verdict

The call

The clearest difference is price: RPN at $3.99 against i41CX+'s $24.99. RPN also leads on iOS requirement (12.0 vs 16.0). i41CX+'s advantage is rating (4.8 vs 4.0) and review sentiment (91% vs 50%). On ads, in-app purchases, monetization model and device support 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

i41CX+ costs $24.99 and RPN $3.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

i41CX+ holds the better App Store score, 4.8 against 4.0. That said, the two scores are not equally well evidenced: i41CX+ has 107 ratings behind it against 4, so its average is the more settled of the two. Written reviews point the same way: 91% of i41CX+'s written reviews are positive against 50% of RPN's.

UpkeepUpdate frequency

i41CX+ ships an update weekly, RPN every 3 months. The most recent releases landed on October 29, 2026 and October 20, 2026 respectively.

Scorecard6 real differences · 4 level
i41CX+ versus RPN: the parameters behind the verdict, then further details
Parameteri41CX+RPN
Price$24.99$3.99 — better
Rating4.8 (107 ratings) — better4.0 (4 ratings)
Positive reviews91.4% of reviews — better50.0% of reviews
Number of ratings107 — better4
Update frequencyWeekly — betterEvery 3 months
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad — betteriPad
Requires iOS16.012.0 — better
Further details — not scored
Size124 MB86 MB
Age rating4+4+
DeveloperAntonio LaganaCuVee Software

Customer experience

i41CX+

All ratings107 ratings
Positive94.4%
Neutral0.9%
Negative4.7%
Written reviews266 reviews
Positive91.4%
Neutral3.0%
Negative5.6%

RPN

All ratings4 ratings
Positive75.0%
Neutral0.0%
Negative25.0%
Written reviews2 reviews
Positive50.0%
Neutral0.0%
Negative50.0%

Bugs and requests

i41CX+

Reported bugs

2 issues
  • Issues with the 41Z math module producing garbled output
  • Scaling problems with overlays

Requested features

4 requests
  • Landscape mode for better button size
  • Haptic feedback for button presses
  • Ability to load and save programs/modules via cloud/email
  • Macros or scripting support

RPN

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

i41CX+

No in-app purchases

None

RPN

No in-app purchases

Questions

Is i41CX+ free?
i41CX+ costs $24.99, with no in-app purchases.
Is RPN free?
RPN costs $3.99, with no in-app purchases.
Which has better reviews, i41CX+ or RPN?
i41CX+ is rated higher. i41CX+ averages 4.8 out of 5 from 107 ratings, while RPN averages 4.0 from 4 ratings.
Do i41CX+ or RPN have ads?
Neither i41CX+ nor RPN shows ads.
Which is updated more often, i41CX+ or RPN?
i41CX+ ships an update weekly, and RPN every 3 months. Most recently, i41CX+ was updated on October 29, 2026 and RPN on October 20, 2026.

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