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 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.

Highlights
  • 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
Read full description

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.

About

RPN

This app simulates a legendary vintage scientific calculator, offering a "live" display of its internal states and a virtual paper tape printer. It allows loading and running original sample programs, with advanced features that can be switched off for an authentic experience.

Highlights
  • Live display of stack and registers
  • Virtual paper tape printer
  • Email or print paper tape
  • Cut/copy/paste display value
  • 30 selectable background images
  • Non-volatile memory
Features
Read full description

RPN-67 NP is the non-programmable version of RPN-67 Pro, the first complete simulation of Hewlett-Packard's HP-67 legendary programmable calculator for iOS. Produced from 1976 to 1982, the HP-67's capability to store programs on magnetic cards, wide array of functions, merged keycodes, indirect addressing and other enhancements made it a huge success among scientists, engineers and other professionals. Thousands of programs were written for it. RPN-67 NP allows you to load and run 25 original HP sample program cards. It lacks the program creation and card management features of the Pro version, as well as its massively expanded array of functions and operations. Apart from these restrictions, RPN-67 NP is a very capable vintage scientific calculator. Features: • "Live" display of stack, memory registers, program counter, flags • Virtual paper tape printer • E-mail or print the paper tape • Cut/copy/paste display value • 30 selectable background images, even add your own. More features the HP-67 never offered: • Non-volatile memory - stack, registers, program • Status indicators for prefix keys (f, g, h, STO, RCL, GTO, DSP) • Keycode-to-command translation while single-stepping a program • Cancel SST or BST operation by sliding your finger off the depressed key All advanced features may switched off with a single setting, allowing you to experience a real HP-67 as closely as possible. For more information visit the RPN-67 website: cuveesoft.ch/rpn67

Screenshots

i41CX4 screens

Verdict

The call

The clearest difference is price: RPN at Free against i41CX's $7.99. RPN also leads on in-app purchases (none vs 4). i41CX's advantage is rating (4.6 vs 3.7) and update cadence (every 5 weeks vs every 5 months). On review sentiment, ads 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

RPN is free to download; i41CX costs $7.99 up front. i41CX sells 4 one-off in-app purchases. RPN asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

i41CX holds the better App Store score, 4.6 against 3.7. That said, the two scores are not equally well evidenced: i41CX has 45 ratings behind it against 3, 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 83% of RPN's.

UpkeepUpdate frequency

i41CX ships an update every 5 weeks, RPN every 5 months. Both last shipped on September 21, 2026.

Scorecard7 real differences · 3 level
i41CX versus RPN: the parameters behind the verdict, then further details
Parameteri41CXRPN
Price$7.99Free — better
Rating4.6 (45 ratings) — better3.7 (3 ratings)
Positive reviews90.5% of reviews — better83.3% of reviews
Number of ratings45 — better3
Update frequencyEvery 5 weeks — betterEvery 5 months
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPad, iPod — betteriPad
Requires iOS13.012.0 — better
Further details — not scored
Size134 MB38 MB
Age rating+44+
DeveloperAntonio LaganaCuVee Software

Customer experience

i41CX

All ratings45 ratings
Positive91.1%
Neutral2.2%
Negative6.7%
Written reviews126 reviews
Positive90.5%
Neutral3.2%
Negative6.3%

RPN

All ratings3 ratings
Positive66.7%
Neutral0.0%
Negative33.3%
Written reviews12 reviews
Positive83.3%
Neutral8.3%
Negative8.3%

In-app purchases

4 purchases

i41CX

One-time4
  • Overlays Upgrade$2.99
  • Printer Upgrade$3.99
  • CAS Upgrade$7.99
Show 1 more
  • i41CX+ Features Upgrade$17.99
None

RPN

No in-app purchases

Questions

Is i41CX free?
i41CX costs $7.99, and also offers in-app purchases.
Is RPN free?
RPN is free to download, with no in-app purchases.
Which has better reviews, i41CX or RPN?
i41CX is rated higher. i41CX averages 4.6 out of 5 from 45 ratings, while RPN averages 3.7 from 3 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 every 5 weeks, and RPN every 5 months. Most recently, i41CX was updated on September 21, 2026 and RPN on September 21, 2026.

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