Comparison

RLM vs DB40X

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

RLM

This advanced scientific calculator emulates the functionality of the HP-15C, offering comprehensive tools for finance, business, statistics, and scientific calculations. It supports programming, equation solving, and unit conversions, optimized for iOS devices.

Highlights
  • Programmable advanced scientific calculator
  • Finance and business calculation menus
  • Statistics and probability functions
  • Complex numbers and matrix operations
  • Unit and currency conversions
  • Equation solver and programming capabilities
Features
Read full description

The RLM-15CX application is a programable advanced scientific calculator. It is based in the Hewlett-Packard HP-15C calculator, but specially designed to bring up the most of your iOS devices and , at the same time, conserving the easy of use and the functionality originally provided by the real calculator. >Finance Menu: •Account Balance: Credit line type account based on cash transactions and interest rates applied. •Amortization: Loan Amortization Schedule for a single loan payment or from several payments at once. •Bond Price & Yield: Bonds calculations in an easy way with all options and values at sight. •Black-Scholes Options: CALL, PUT and “Greeks” calculations of the Black-Scholes European option valuation model. •Equal Periods Cash Flows: Solve problems where different cash flows occur at regular time intervals. •Unequal Periods Cash Flows: Solve problems where different cash flows occur at different dates. •Depreciation: Calculates depreciation with SL, SOYD, DB or MACRS methods and conventions. values at sight. •Interest Rates: Nominal and effective interest conversion. •Time Value of Money: Compound Interest problems involving money earning interest over a period of time. >Business Menu: •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 on-line rates. •Percents & Margins: Calculates %Change, %Total and Business margins. >Date / Time Menu: Calculates Date and Time intervals with all values at sight. >Statistics Menu: •One-Variable Statistics: Calculations for one variable data samples. •Two-Variable Statistics: Calculations for two variables data samples. •Curve Fitting: 6 Regression models to fit a curve based on two variables data samples. •Probability: Combinations, permutations, Normal, Exponential, t-Student and Weibull probability distributions. >Scientific Menu: •Complex Numbers: Operations and functions with complex numbers. •Matrix: view, create or edit matrices with real or complex elements. •Plane Triangle: Solves a two dimensional triangle (ASA,SAS,SSA and SSS). •Spherical Triangle: Solves a triangle in a sphere’s surface (AAA,AAS,ASA,SAS,SSA and SSS). •Universal Constants: All the NIST-CODATA fundamental physical constants. •Vectors 3D: Operations and functions with vectors in Cartesian, Spherical or Cylindrical coordinates. >Convert Menu: •Angles & Polar: Convert angles between DEG,RAD,GRAD,DMS or Slope % & Polar-Rectangular coordinates. •Currencies: world currencies conversions with manual input or on-line current rates. •Interest Rates: Nominal and effective interest conversion. •Units: Physical units conversions. >Program Menu: Create, edit or load previously saved programs. >Solver Menu: Solve arbitrary algebraic equations entered and saved in the equation editor and creates a menu with all the variables to solve any of them. >Utilities Menu: •General Settings: Customize the calculator to your preference. •Memory Content: Shows all memory content edit, backup or restore. •Help Documents: learn by example about all menus. >Editors: submenu to select data editors. 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

About

DB40X

A high-precision scientific calculator inspired by the HP48 series, offering arbitrary precision computations, complex numbers, vectors, matrices, and graphing. It supports RPN and algebraic operations, with over 1000 built-in functions and a hyperlinked help system.

Highlights
  • Arbitrary precision computations
  • RPN and algebraic operations
  • Complex numbers, vectors, and matrices
  • Graphing and plotting
  • Engineering units and conversions
  • Hyperlinked help system
Features
Read full description

DB40X is a high-precision scientific calculator compatible with DB48X and inspired by the legendary HP48 series from Hewlett-Packard. It is not an emulator, but a redesign from scratch, which is faster, and delivers never seen before capabilities like computations in arbitrary precision. Like the original HP48, DB40X supports an unlimited stack, RPN and algebraic operations, complex numbers, based numbers, vectors, matrices, text, symbolic computations, numerical solving and integration, graphing and plotting, statistics, engineering units, and well over 1000 built-in functions. DB40X adds several HP50G capabilities, including a library of equations and constants covering mathematics, physics or chemistry. Using modern technologies, DB40X goes well beyond the original HP48 in many ways: - It is significantly faster, uses less memory, and features a higher-resolution 240x400 pixels graphical display. - Integer and decimal values can have an arbitrarily large number of digits, so you can compute log(pi) with 200 digits in a few keystrokes. - The six function keys feature up to three function per key, giving quick access to up to 18 related functions at a time. - Complex numbers can mix and match polar and rectangular form. - Symbolic operations extend to complex numbers, vectors and matrices. - Based numbers can be in any base from 2 to 36, and support any number of bits, making it easy to emulate a 23-bit or 512-bit processor. - Text is represented using Unicode instead of the proprietary HP encoding, facilitating data exchange with the rest of the world. - Multiple graphs can be distinguished using bitmap patterns. - Engineering units include all the modern evolutions of the SI system, and can be configured by the user, e.g. to integrate currency units with the exchange rate du jour. Converting between USD/hour and EUR/day has never been so easy! - A built-in hyperlinked help system documents functions simply by holding the corresponding key, and combine a quick start guide, a user manual and a reference manual. DB40X will run many user RPL programs as is. However, since it is not an emulator, it will not run any HP binary object, and notably will not run HP48 games or anything involving system RPL. Version 0.7.14 is an early-access release. Please consult https://github.com/c3d/db48x/blob/stable/doc/5-Unimplemented.md for a list of HP48 commands that are not yet implemented. DB40X is part of a family of compatible RPL calculators that include DB48X and DB50X. DB40X lacks the ability to write programs or data to disk, and RPL programs are limited to 40K.

Screenshots

RLM4 screens
DB40X3 screens

Verdict

The call

The clearest difference is rating: DB40X at 4.7 against RLM's 4.1. DB40X also leads on in-app purchases (none vs 4). RLM's advantage is review sentiment (80% vs 67%). On price, ratings volume, update cadence and ads 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

Both are free to download. RLM sells 4 in-app purchases, starting at $0.49 per month. DB40X asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

DB40X holds the better App Store score, 4.7 against 4.1. Both are backed by a comparable volume of ratings — 17 and 7 respectively. Written reviews complicate that: 80% of RLM's written reviews are positive against 67% of DB40X's, so the app with the better star average is not the one people write more warmly about.

UpkeepUpdate frequency

RLM ships an update monthly, DB40X every 3 weeks. The most recent releases landed on September 10, 2026 and June 4, 2026 respectively.

Scorecard4 real differences · 6 level
RLM versus DB40X: the parameters behind the verdict, then further details
ParameterRLMDB40X
PriceFreeFree
Rating4.1 (17 ratings)4.7 (7 ratings) — better
Positive reviews80.0% of reviews — better66.7% of reviews
Number of ratings17 — better7
Update frequencyMonthlyEvery 3 weeks — better
AdsNoNo
In-app purchasesYesNo — better
MonetizationFree with in-app purchasesFree — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.014.0 — better
Further details — not scored
Size6 MB7 MB
Age rating4+4+
DeveloperR.L.M. SoftwareChristophe de Dinechin

Customer experience

RLM

All ratings17 ratings
Positive70.6%
Neutral11.8%
Negative17.6%
Written reviews15 reviews
Positive80.0%
Neutral13.3%
Negative6.7%

DB40X

All ratings6 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive66.7%
Neutral33.3%
Negative0.0%

In-app purchases

4 purchases

RLM

Subscriptions3
  • Monthly Subscription$0.491 Month
  • Semi-Annual Subscription$2.996 Months
  • Annual Subscription$5.991 Year
One-time1
  • One-Time Purchase$9.99
None

DB40X

No in-app purchases

Questions

Is RLM free?
RLM is free to download, with in-app purchases available.
Is DB40X free?
DB40X is free to download, with no in-app purchases.
Which has better reviews, RLM or DB40X?
DB40X is rated higher. RLM averages 4.1 out of 5 from 17 ratings, while DB40X averages 4.7 from 7 ratings.
Do RLM or DB40X have ads?
Neither RLM nor DB40X shows ads.
Which is updated more often, RLM or DB40X?
RLM ships an update monthly, and DB40X every 3 weeks. Most recently, RLM was updated on September 10, 2026 and DB40X on June 4, 2026.

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