i41CX+ vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i41CX+
This advanced RPN scientific calculator offers a virtual thermal printer, workstation-class CAS, and full emulation of the HP-41CX. It supports a vast library of modules and programs, enhanced with iOS features, customizable skins, and iCloud syncing for powerful on-the-go calculations.
- RPN logic with 4-element stack
- Virtual thermal printer/plotter
- Workstation-class Computer Algebra System (CAS)
- Full HP-41CX emulation and module support
- Programmable with virtually unlimited lines
- Customizable skins and keyboard overlays
- iCloud syncing for files and settings
Read full descriptionHide 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.
RPN
This app is a photo-realistic simulation of a classic Hewlett-Packard programmable business calculator. It offers advanced programming features, extensive register memory, and a library of pre-installed programs for various financial and statistical calculations.
- Photo-realistic look-and-feel
- Programmable with subroutines and flags
- 20 registers with unlimited store/recall
- Indirect register addressing
- Program library and sharing
- Financial and statistical functions
- Date and calendar calculations
Read full descriptionHide full description
RPN-38 CX is the first photo-realistic simulation of Hewlett-Packard's popular high-end programmable business calculator HP-38C for the iPhone. Produced from 1979 through 1983, it was the "Chive" member of the third-generation HP calculators known as the "Spice" series. While the simulator works like the original calculator, a number of carefully designed extensions make it a lot easier to use. RPN-38 CX is fully compatible with the HP-12C, except for calculations and programs involving Bonds and Depreciation. Features: • Photo-realistic look-and-feel • Programmable (99 steps, program memory not shared with register memory) • Subroutines, flags, loop control, extended conditional branching • Insert and delete steps with automatic address correction • 20 registers, "continuous", with unlimited store/recall arithmetic • Indirect register addressing • Register view • Program listing view • Program library view • Additional functions (nominal and effective interest rate) • Shortcuts for often-used key combinations • Store and retrieve any number of programs • Sharing: e-mail, AirDrop, Dropbox, copy, paste, print • 40 programs pre-installed Calculator functions: • Percentage (%, ∆%, %Total) • Simple and Compound Interest • Optional odd periods (like HP-12) • Nominal/Effective interest rate conversion • Amortization • Discounted Cash Flow Analysis • Net Present Value, Internal Rate of Return • Date and Calendar (actual or 30/360 day basis) • Statistics (mean, weighted mean, standard deviation) • Linear Regression • Additional functions not found on the HP-38: - Subroutines, flags, loop control, random number, Pi, Log, x² and more Details: cuveesoft.ch/rpn38
Screenshots
Verdict
The clearest difference is price: RPN at $1.99 against i41CX+'s $24.99. RPN also leads on rating (5.0 vs 4.8) and review sentiment (100% vs 91%). i41CX+'s advantage is update cadence (every 6 days vs every 2 months) and ratings volume (109 vs 7). 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
i41CX+ costs $24.99 and RPN $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.
RPN holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: i41CX+ has 109 ratings behind it against 7, 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 100% of RPN's.
i41CX+ ships an update every 6 days, RPN every 2 months. The most recent releases landed on November 8, 2026 and November 2, 2026 respectively.
| Parameter | i41CX+ | RPN |
|---|---|---|
| Price | $24.99 | $1.99 — better |
| Rating | 4.8 (109 ratings) | 5.0 (7 ratings) — better |
| Positive reviews | 91.4% of reviews | 100.0% of reviews — better |
| Number of ratings | 109 — better | 7 |
| Update frequency | Every 6 days — better | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 16.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 124 MB | 12 MB |
| Age rating | 4+ | 4+ |
| Developer | Antonio Lagana | CuVee Software |
Customer experience
i41CX+
RPN
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
i41CX+
No in-app purchases
RPN
No in-app purchases









