i41CX vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i41CX
This app offers a powerful RPN scientific calculator experience, functionally equivalent to a renowned model. It provides extensive memory registers, over 300 built-in functions, and programmability. Advanced features can be unlocked via in-app purchases.
- RPN logic with 4-element stack
- 319 main and 124 extended memory registers
- Over 300 built-in functions
- Programmable up to 2000 lines
- User-definable keyboard
- Bluetooth keyboard support
- Device integration features
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i41CX is the same powerful advanced programmable RPN scientific calculator as the highly acclaimed i41CX+ but without the latter’s incredibly advanced capabilities such as the printer, expansion, CAS, etc. It is functionally equivalent to the world-renowned HP-41CX and inherits all of the i41CX+ usability features including extremely responsive and animated key clicks, audible key feedback sounds, optimally spaced keys for accurate input, traditional and upbeat modern diverse set of skins, etc. If you are looking for a powerful programmable RPN scientific calculator but don’t need all of the capabilities of i41CX+ then i41CX is for you. And best of all, if you ever decide that you need the more advanced capabilities of i41CX+ you can enable them using secure in-app purchases right within the app! FEATURES: • RPN logic with a 4 element deep memory stack • 319 main and 124 extended memory registers • Over 300 built-in functions, including nearly 100 functions created specifically for i41CX • Time, calendar, alarm, and stopwatch functions • Rich set of functions and algorithms: numerical, mathematical, statistical, and much more • 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 - Over 2000 lines • User definable keyboard • Ability to operate the calculator using a Bluetooth keyboard • Device integration: external display mirroring, copy and paste, GPS, accelerometer, digital compass, time and date synchronization, and much more • iOS 8 Notification Center widget • Sound support including synthetic tones and interface sounds • Support for calculator skins and optional mini stack display • Adjustable sound volume and display colors • Usage & Examples table with usage tips and examples • Quick reference guide of all built-in functions • Beautiful and clean user interface *********************************************************** A comprehensive FAQ is available at http://alsoftiphone.com/i41CX. 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
Experience a faithful simulation of the groundbreaking HP-65 programmable calculator on your iPhone. This app offers virtual program and data cards, a paper tape printer, and a robust card manager. Explore four distinct operating modes, including an enhanced "Super-65" option.
- Virtual program and data cards
- Virtual paper tape printer with AirPrint
- Database-driven card manager
- Create, delete, and organize unlimited cards
- Sharing via email, AirDrop, Dropbox, iTunes
- Paste and run existing HP-65 listings
- Four distinct operating modes
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World's first pocket computer! Now running on your iPhone. RPN-65 SD is the iPhone version of RPN-65 Pro, 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 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 iPhone. With over 180 original HP programs included with the app, you can get started right away. "A work of art. Fantastic!" (MacBreak Weekly, episode 572) Features: • Virtual program and data cards • Virtual 2000-line 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, iTunes, copy, paste, print • Paste existing HP-65 listings into RPN-65 and run them • "Live" display of stack, memory registers, program counter, flags • Reads program and data cards created by RPN-65 Pro • Reads data cards created by RPN-67 Pro/SD and RPN-97 Pro Run RPN-65 SD in any of 4 modes: 1 - Just like the original HP-65 2 - Like the original HP-65, but at much higher speed 3 - With many user-interface improvements, like backstep key or 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
Verdict
The clearest difference is in-app purchases: RPN at none against i41CX's 4. RPN also leads on price ($2.99 vs $7.99) and rating (5.0 vs 4.7). i41CX's advantage is update cadence (weekly vs every 4 months) and ratings volume (47 vs 8). On ads 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 $7.99 and RPN $2.99 up front. i41CX sells 4 one-off in-app purchases. RPN asks for nothing beyond the download.
RPN holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: i41CX has 47 ratings behind it against 8, so its average is the more settled of the two. Written reviews point the same way: 90% of i41CX's written reviews are positive against 100% of RPN's.
i41CX ships an update weekly, RPN every 4 months. The most recent releases landed on October 29, 2026 and October 31, 2026 respectively.
| Parameter | i41CX | RPN |
|---|---|---|
| Price | $7.99 | $2.99 — better |
| Rating | 4.7 (47 ratings) | 5.0 (8 ratings) — better |
| Positive reviews | 90.5% of reviews | 100.0% of reviews — better |
| Number of ratings | 47 — better | 8 |
| Update frequency | Weekly — better | Every 4 months |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Free with in-app purchases — better | Paid |
| Devices | iPhone, iPad | iPhone, iPod |
| Requires iOS | 16.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 135 MB | 62 MB |
| Age rating | 4+ | 4+ |
| Developer | Antonio Lagana | CuVee Software |
Customer experience
i41CX
RPN
In-app purchases
i41CX
- Overlays Upgrade$2.99
- Printer Upgrade$3.99
- CAS Upgrade$7.99
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- i41CX+ Features Upgrade$17.99
RPN
No in-app purchases









