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
This app is a detailed simulation of a 1973 scientific calculator, offering a photorealistic interface and all original functions. It includes powerful enhancements for modern use, such as complex number support and advanced date calculations.
- Photorealistic calculator simulation
- Full HP-45 function implementation
- Complex number support
- Advanced date and time functions
- Printer simulation for calculation records
- Stopwatch functionality
- Cut/copy/paste display values
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RPN-45 SD is a complete simulation of the scientific hand-held calculator HP-45 from 1973. Powerful enhancements turn the calculator into an amazingly useful tool for the 21st century. Features: • Photo-realistic look based on an existing device • Original LED display or high-contrast LCD display • Printer to keep a record of calculations • Animated keys with adjustable click sound and visual feedback • Simulation of the HP-45's computation times (may be disabled) • All functions and operations of the HP-45 fully implemented • "Secret" stopwatch implemented, extensible from 12 to 100 hours capacity • Stopwatch may be preset to current time • Swipe left across display to correct wrong number entries • Cut/copy/paste of display value • Tap display to show stack and all memory registers • Complex numbers may be used in almost all operations • Non-volatile stack and registers • 18 storage locations (9 in complex number mode) • Exponentiation and factorial accept any values (incl. complex) • Optional hyperbolic functions • Logarithm to any base (incl. complex) • Solve linear equations in two or three unknowns • Solve quadratic and cubic equations • Normal distribution, Pearson correlation coefficient of paired variables • Linear regression with estimates • Weighted mean • Permutation, Combination (binomial coefficient) • Integer and fractional part of a number • Display rounding • Random numbers in any range, integer or real • Day of the week of any date between Jan 1, 0001 and Dec 31, 9999 • Easter date for any year between 1583 and 4099 • Support for Julian dates • Date and day of the week a number of days away (past or future) • Number of days between any two dates • Last Stack operation • Show display value in hexadecimal • Percentage of sum • Register arithmetic includes summation registers and LAST x • Indicators for active prefix keys • Angular mode indicator • Localized decimal point • Thousand's separator • Clear all registers • Backup registers in a protected area Double-tap the display for some basic hints. Also available for iPad (RPN-45 HD). For more information, a manual and sample calculations visit the RPN-45 website: cuveesoft.ch/rpn45/en What users said: "Have been using HP RPN calculators since HP-35 first came out. The CuVée versions for Apple products are the best emulations by far. I have, and regularly use, them all." "This app is a great emulator of the classic HP-45 Scientific Calculator, in look, feel and function. It keeps getting better and better with each update." "This is the most like the real thing that I've used. I've bought others but keep coming back to this App. It's photorealistic, the LEDs appear the way the real ones do, and the buttons almost give the same satisfying feedback of the real thing."
Screenshots
Verdict
The clearest difference is in-app purchases: RPN at none against i41CX's 4. RPN also leads on price ($1.99 vs $7.99) and iOS requirement (12.0 vs 16.0). i41CX's advantage is update cadence (weekly vs every 4 months) and rating (4.7 vs 4.3). 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 $1.99 up front. i41CX sells 4 one-off in-app purchases. RPN asks for nothing beyond the download.
i41CX holds the better App Store score, 4.7 against 4.3. Both are backed by a comparable volume of ratings — 47 and 15 respectively. Written reviews point the same way: 90% of i41CX's written reviews are positive against 82% of RPN's.
i41CX ships an update weekly, RPN every 4 months. The most recent releases landed on October 31, 2026 and November 1, 2026 respectively.
| Parameter | i41CX | RPN |
|---|---|---|
| Price | $7.99 | $1.99 — better |
| Rating | 4.7 (47 ratings) — better | 4.3 (15 ratings) |
| Positive reviews | 90.5% of reviews — better | 81.8% of reviews |
| Number of ratings | 47 — better | 15 |
| 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 | 14 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









