Comparison

Free42 vs RLM

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

Head to head
About

Free42

This application is a faithful re-implementation of the HP-42S scientific calculator and its associated printer. It offers full functionality without requiring original HP ROM images and is an open-source project.

Highlights
  • HP-42S calculator simulation
  • HP-82240 printer simulation
  • Open source project
  • No HP ROM required
  • Complete rewrite
Features
Read full description

Free42 is a re-implementation of the HP-42S calculator and the HP-82240 printer. It is a complete rewrite, not using any HP code, and it does not require an HP-42S ROM image. Free42 is an Open Source project. The executables and source code are released under the terms of the GNU General Public License, version 2. All third-party code used in Free42 is either in the public domain, or licensed under terms compatible with GPLv2, or used with the authors' permission.

About

RLM

This aviation computer app offers a comprehensive suite of tools for pilots. It calculates various flight parameters, including altitude, airspeed, ground speed, wind components, and weight & balance. The app also features unit and currency conversions, making it a versatile utility for aviation professionals.

Highlights
  • Altitude & Cloud Base Calculations
  • Airspeed & Ground Speed Calculations
  • Wind Component & Correction Tools
  • Weight & Balance Calculations
  • Unit & Currency Conversion
  • Holding Pattern & Flight Plan Tools
Features
Read full description

The RLM-Flight app is the ultimate aviation computer. Designed with a clear beautiful interface and easy to use through direct menu selection with all variables at sight converting it in the most powerful, versatile and useful aviation computer you may have in your iOS device. The RLM-Flight has a extensive Menu System: >Altitude & Cloud Base Worksheets: Calculate Pressure Altitude, Density Altitude, Barometric Pressure or Outside Temperature with or without humidity. Also calculates the Cloud Base above ground and Clouds Temperature knowing the Outside Temperature and Dew Point. >Standard Atmosphere: Calculate the Altitude, Temperature or Pressure and the Air Density and Speed of Sound in the International Standard Atmosphere (ISA). > Airspeed Calculations: Calculate the True Air Speed, Calibrated Air Speed, Outside Temperature, Mach number, Total Air Temperature or Pressure Altitude. >Ground Speed & Fuel Rate: Calculate the Ground Speed, Distance, Duration or Fuel consumption. >Glide & Climb/Descent: Calculate Horizontal Distance, Glide Ratio, Descent or Climb Altitude, Angle and Ratio. >Wind Components: Calculate Cross Wind, Head Wind, Run Way, Wind Speed or Wind Direction. >Wind Correction: Calculates the Ground Speed, True Course, True Air Speed, True Heading, Wind Speed or Wind Direction and the Wind Correction Angle. >Compass Heading: Calculate True Heading, Magnetic Heading, Compass Heading, Variation or Deviation. >Holding Pattern & From-To: Calculate the type of entry necessary and the inbound heading to enter in a holding pattern given by the airplane Heading, the Holding Radial and the standard turn (left or right). Also, convert the course from a location into the course to the same location. >Rhumb Line: Calculate the True Course, Rhumb Line Distance and the Great Circle Distance for flight paths specified by latitude and longitude. >Flight Plan: Calculate the Total Distance, Estimated Time in Route, Estimated Time of Arrival and Fuel Burned in a cross country flight composed of an arbitrary number of legs. >Weight & Balance: Calculates the total weight and the resulting center of gravity of an airplane base on the loads arms, weights and/or moments of different items including the empty aircraft weight and center of gravity, pilots, passengers, fuel and cargo areas. >Weight Shift & %MAC: Calculate the change in Center of Gravity, change in Weight, change in Arm or total Weight given the others. Also calculate the %MAC, Center of Gravity, Mean Aerodynamic Chord or Leading Edge of MAC given the others. >Units Conversion: powerful and completely customizable physical units conversion calculations. >Currency Conversion: to calculate currency exchanges between two selected world currencies and common crypto currencies with manual or on-line rates. > Math Functions: to apply scientific functions to the displayed number including angles conversion, trigonometric functions, logarithmic function, decimal hour to hour:minute:seconds, etc. 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: THE “RLM-Flight” SOFTWARE IS PROVIDED TO YOU ON AN "AS IS" BASIS. THE SOFTWARE IS NOT CERTIFIED BY ANY AUTHORITY AT THE MOMENT AND THE USER ASUMES ALL THE RESPONSIBILITY OF IT USE. THE LICENSOR DOES NOT REPRESENT OR WARRANT THAT THE SOFTWARE CALCULATIONS OR DATA MADE WILL BE FREE FROM MISTAKES OR ANY OTHER DEFECTS OR ERRORS AND THAT ANY SUCH EFFECTS OR ERRORS WILL BE CORRECTED, OR THAT IT WILL OPERATE WITHOUT INTERRUPTION. YOU AGREE THAT YOU ARE SOLELY RESPONSIBLE FOR ALL COSTS AND EXPENSES ASSOCIATED WITH RECTIFICATION, REPAIR OR DAMAGE CAUSED BY SUCH DEFECTS, ERRORS OR INTERRUPTIONS.

Screenshots

Free423 screens
RLM4 screens

Verdict

The call

The clearest difference is in-app purchases: Free42 at none against RLM's 1. Free42 also leads on ratings volume (283 vs 2) and update cadence (weekly vs every 3 weeks). RLM's advantage is rating (5.0 vs 4.8). On price, ads, monetization model 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. RLM sells 1 one-off in-app purchase. Free42 asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

RLM holds the better App Store score, 5.0 against 4.8. That said, the two scores are not equally well evidenced: Free42 has 283 ratings behind it against 2, so its average is the more settled of the two.

UpkeepUpdate frequency

Free42 ships an update weekly, RLM every 3 weeks. The most recent releases landed on September 4, 2026 and September 10, 2026 respectively.

Scorecard5 real differences · 5 level
Free42 versus RLM: the parameters behind the verdict, then further details
ParameterFree42RLM
PriceFreeFree
Rating4.8 (283 ratings)5.0 (2 ratings) — better
Positive reviews93.8% of reviews—
Number of ratings283 — better2
Update frequencyWeekly — betterEvery 3 weeks
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFreeFree
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better15.0
Further details — not scored
Size9 MB6 MB
Age rating4+4+
DeveloperThomas OkkenR.L.M. Software

Customer experience

Free42

All ratings283 ratings
Positive93.6%
Neutral2.5%
Negative3.9%
Written reviews161 reviews
Positive93.8%
Neutral1.9%
Negative4.3%

RLM

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

Free42

Reported bugs

2 issues
  • Occasional issues with Solver function
  • Store and Recall functions not working properly

Requested features

3 requests
  • Display all registers (X, Y, Z, T, Last X) simultaneously
  • Ability to share/transfer programs between devices
  • Improved use of screen real estate on larger displays

RLM

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Free42

No in-app purchases

1 purchases

RLM

One-time1
  • Lifetime Full Access$9.99

Questions

Is Free42 free?
Free42 is free to download, with no in-app purchases.
Is RLM free?
RLM is free to download, with in-app purchases available.
Which has better reviews, Free42 or RLM?
RLM is rated higher. Free42 averages 4.8 out of 5 from 283 ratings, while RLM averages 5.0 from 2 ratings.
Do Free42 or RLM have ads?
Neither Free42 nor RLM shows ads.
Which is updated more often, Free42 or RLM?
Free42 ships an update weekly, and RLM every 3 weeks. Most recently, Free42 was updated on September 4, 2026 and RLM on September 10, 2026.

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