Comparison

i41CX+ vs RLM

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
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

RLM

This app offers a comprehensive suite of calculators for finance, business, science, and general use. It includes specialized worksheets for loans, investments, statistics, and complex mathematical functions, designed to leverage iOS device capabilities.

Highlights
  • Finance worksheets (amortization, bond pricing, options)
  • Business calculations (bill split, break-even, currency)
  • Statistical analysis (probability, regressions)
  • Scientific functions (complex numbers, vectors)
  • Unit and currency conversions
  • Equation solver
  • Date and time calculations
Features
Read full description

The RLM-17BX is a general purpose calculator with a special focus in finance, business and science. It is designed to bring up the most of your iOS devices with an extensive set of worksheets and enhancements to cover most of the functions generally needed by financial, business, mathematical, engineering and scientific professionals. >Finance Worksheets: •Account Balance: Calculates the Balance of cash transactions and interest applied at arbitrary dates. •Amortization: Loan Amortization Schedule for a single or several loan payments. •Bond Price & Yield: Calculates the Price, Yield and Effective Duration of a Bond. •Black-Scholes Options: Calculates the CALL, PUT and “Greeks” values of a Black-Scholes European option. •Depreciation: Calculates depreciation with SL, SOYD, DB or MACRS methods and conventions. •Time Value of Money: Calculates compound Interest problems. >Business Worksheets: •Bill-Tip-Split: Calculates the sharing of a Bill with Tip. •Break-Even: Analyze the following relation: Profit = (Price - Var.Cost) • Units - Fix.Cost •Currency Exchange with manual or on-line rates. •Percents & Margins: Calculates %Change, %Total and Business margins. >Cash Flows Worksheets: •Equal Periods: Calculations with Cash Flows occurring at regular time intervals. •Unequal Periods: Calculations with Cash Flows occurring at arbitrary dates. >Statistics Worksheets: •Probability: Combinations, permutations and Normal, Exponential, t-Student and Weibull probability distributions. •One-Variable Statistics: Calculations for one variable data samples. •Two-Variable Statistics: Calculations for two variables data samples. •Curve Fitting: Regression models to fit a curve based on two variables data samples. >Scientific Worksheets: •Complex Numbers: Operations and functions with complex numbers. •Logarithms, Trigonometric, Hyperbolic and Number Alteration functions. •Triangle Solution: Solves a Plane & Spherical triangles. •3D Vectors: Operations and functions with vectors in Cartesian, Spherical or Cylindrical coordinates. •Universal Constants: All the NIST-CODATA physical constants values and descriptions. •Units Conversion: Physical units conversion completely customizable. >Conversion Worksheets: •Angles: Convert angle between DEG,RAD,GRAD,DMS and Slope %. •Currencies: world currencies conversions with manual input or on-line current rates. •Interest Rates: Nominal and effective interest conversion. •Polar-Rectangular: Coordinates conversion. •Units: Physical units conversions. >General Worksheets: •Date: Calculates days between dates with Actual, 360 or 365 days calendars. •Time: Calculates time intervals between different times. •Solver: Calculates arbitrary equations entered as text expression to solve any of the variables knowing the others. •Storage Registers: Store and perform operations directly over the calculators storage registers. •Memory Content: Clear, Back-Up or Restore part or all of the Calculator's memory. •General Settings: Customize many aspects of the calculator including formats & feedbacks. •Help Documents: Description and examples of all the calculator worksheets and features. >Editors Worksheets: To create or edit data •(Date,Trx) List: Transactions and the dates they occurs for the "Account Balance Worksheet". •(Date.CF) List: Cash flows and the dates they occurs for the "Unequal Periods Cash Flows Worksheet". •(X,N) List: Cash flows and repetitions for the "Equal Periods Cash Flows Worksheet". •(X,Y) List: X and Y data samples for the Statistics worksheets. •Solver Equation: Algebraic expression for use in the "Solver" worksheet. •Units Database: Customize the "Units" worksheet. System requirements: iOS 15.0 or above. 30 days Free-Trial. In-App-Purchase: One-Payment for life. License Agreement: http://www.apple.com/legal/itunes/appstore/dev/stdeula Disclaimer: THIS IS NOT A HEWLETT PACKARD CALCULATOR, AND IS NOT SPONSORED IN ANYWAY BY HEWLETT PACKARD OR ANY OF ITS SUBSIDIARIES.

Screenshots

i41CX+4 screens
RLM4 screens

Verdict

The call

The clearest difference is price: RLM at Free against i41CX+'s $24.99. i41CX+'s advantage is rating (4.8 vs 3.9) and review sentiment (91% vs 53%). On update cadence, ads, device support 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

RLM is free to download; i41CX+ costs $24.99 up front. RLM sells 4 in-app purchases, starting at $0.49 per month. i41CX+ asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

i41CX+ holds the better App Store score, 4.8 against 3.9. That said, the two scores are not equally well evidenced: i41CX+ has 108 ratings behind it against 10, 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 53% of RLM's.

UpkeepUpdate frequency

i41CX+ ships an update every 5 weeks, RLM monthly. The most recent releases landed on October 19, 2026 and October 15, 2026 respectively.

Scorecard6 real differences · 4 level
i41CX+ versus RLM: the parameters behind the verdict, then further details
Parameteri41CX+RLM
Price$24.99Free — better
Rating4.8 (108 ratings) — better3.9 (10 ratings)
Positive reviews91.3% of reviews — better53.3% of reviews
Number of ratings108 — better10
Update frequencyEvery 5 weeksMonthly — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.015.0
Further details — not scored
Size124 MB6 MB
Age rating4+4+
DeveloperAntonio LaganaR.L.M. Software

Customer experience

i41CX+

All ratings108 ratings
Positive94.4%
Neutral0.9%
Negative4.6%
Written reviews265 reviews
Positive91.3%
Neutral3.0%
Negative5.7%

RLM

All ratings10 ratings
Positive70.0%
Neutral10.0%
Negative20.0%
Written reviews15 reviews
Positive53.3%
Neutral20.0%
Negative26.7%

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

RLM

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

i41CX+

No in-app purchases

4 purchases

RLM

Subscriptions3
  • Monthly Virtual Battery$0.491 Month
  • Semi-Annual Subscription$2.996 Months
  • Annual Subscription$5.991 Year
One-time1
  • Lifetime Purchase$9.99

Questions

Is i41CX+ free?
i41CX+ costs $24.99, with no in-app purchases.
Is RLM free?
RLM is free to download, with in-app purchases available.
Which has better reviews, i41CX+ or RLM?
i41CX+ is rated higher. i41CX+ averages 4.8 out of 5 from 108 ratings, while RLM averages 3.9 from 10 ratings.
Do i41CX+ or RLM have ads?
Neither i41CX+ nor RLM shows ads.
Which is updated more often, i41CX+ or RLM?
i41CX+ ships an update every 5 weeks, and RLM monthly. Most recently, i41CX+ was updated on October 19, 2026 and RLM on October 15, 2026.

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