# Free42 — user reviews > 161 indexed App Store user reviews of Free42 by Thomas Okken, rated 4.80/5 from 283 ratings. - Source: https://appshunter.io/ios/app/free42/id337692629/reviews - App overview in markdown: https://appshunter.io/ios/app/free42/id337692629.md - Rating breakdown: 5★ 254 · 4★ 11 · 3★ 7 · 2★ 3 · 1★ 8 ## What do users think of Free42? Overall sentiment: positive **Pros** - 🚀 Faithful reproduction of HP42S - 👍 Identical to physical calculator - 👍 Runs all original programs - 👍 Convenient to have on phone - 👍 Haptic feedback on button presses - 👍 Customizable skins - 👍 Actively maintained and updated **Cons** - 🐛 Screen not filling entire display on newer devices - 🔇 Configurable key click sound missing - 🔇 Lack of loud click sound feedback **Commonly reported bugs** - Occasional issues with Solver function - Store and Recall functions not working properly **Most requested features** - 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 ## Newest reviews (18 of 161) ### 5/5 — Love this calculator *2023-12-28* I’ve been a fan of RPN for over 40 years. This calculator works great. I don’t typically use it for much more than simple calculations but I use it daily. I absolutely love the haptic feedback with key presses. It’s gives great indication when you’ve typed a number. ### 5/5 — Great app *2023-12-04, version 3.1.2* Terrific! ### 5/5 — I love it! *2023-04-11* Thanks for writing this lovely peace of software! ### 5/5 — Great RPN Calculator *2023-04-06, version 3.0.19* I first started with my first RPN calculator when I worked in electrical engineering in the eighties with my HP15C. I used it very extensively, writing time saving programs for my job. (Also, the approximately $90 or so purchase price at the time, with a young family really hurt!) Although, my present position for the last twenty years doesn’t require anything advanced, RPN is still my first choice for a calculator. The “Free42” RPN calculator is easy to use & works well. I’m sorry to say that I haven’t used very many of the advanced functions. I have also loaded the windows version on my computer at work, with a skin that is similar to the HP15C (for sentimental reasons…). Also browsing the developer’s website, I was surprised to see that this software was created in 2004, has had many updates & is available for android, iPhone, Windows, Linux & Mac. Looking thru the updates listed on his website, this developer is very committed to this product. (it’s sad, my real HP15C calculator is just gathering dust in my dresser top junk drawer, half the time, the batteries die due to drainage from lack of use, it’s just too easy to reach for my iPhone that’s already in my pocket) My only complaint is the name. Free42 makes this product sound cheap & junky, it is not! Please consider a better name. ### 5/5 — Richtig guter Taschenrechner *2022-12-31* Auf meinem Schreibtisch liegen seit fast 30 Jahren Taschenrechner von HP. Am häufigsten nutze ich den HP 32Sii. Mit der App muss ich auch unterwegs nicht auf den Komfort eines RPN-Taschenrechners verzichten, sondern habe ihn allzeit griffbereit dabei. Neu: Mit dem Plus42 gibt es jetzt einen großen Bruder des Free42, der das große Display neuer iPhones optimal ausnutzt. Den sollte man allein schon kaufen, um die großartige Arbeit des Entwicklers zu würdigen. ### 5/5 — Needs shake to clear stake *2022-11-22, version 3.0.16* Terrific, but will get 5 stars when it has the shake to clear stack that 42S had. But this app is 64 bit and 42S is out of the app store. ### 5/5 — Needs getting used to *2022-11-07* The RPN style of.calculators needs some getting used to. No ads and no paywalls are some bonuses if you are willing to get your hands dirty. ### 5/5 — I feel so guilty. *2022-10-15* I’ve been using Free 42 for years, I’ve never paid a penny! I paid for other HP emulators that I only sparingly used before deleting. At least add a menu item in ‘about’ that we can buy you a coffee!😊 **Developer response:** For donations, I have a PayPal link on my web site. Or maybe you would also enjoy my other calculator app, Plus42. Thank you! ### 5/5 — Awesome app! *2022-10-03, version 3.0.15* I was elated to find this FREE app. I used a HP41C in college many moons ago and absolutely love RPN. Later on I used the HP42 at my job. Kudos to the developer for creating this fabulous app! ### 5/5 — Probably the best *2022-06-19* Yep. Seriously. This is one of the very best calculators available for download on the internet. As a FREE app, perhaps only the Wp-34S and a handful of others come close; and the few that do are almost exclusively based upon ground-breaking machines produced by Hewlett Packard. Highlighting Free42's capabilities could fill a small book - and it's better than the machine it's based upon! Thankfully, manuals, web-sites and forums exist to support this magnificent piece of work, and although exploring the wealth of information is not essential, it is educational and highly rewarding. Different skins are available too. They can be swapped in seconds, even during a calculation. And not only do they alter the appearance; in many cases they make subtle modifications to provide quicker access to various functions. Bottom line: Hundreds of calculators can perform basic arithmetic; but some do a whole lot more… ### 5/5 — Very Nice *2022-06-14* Works like it should! Great tool & good fun to use. Thank you ### 4/5 — Love it but *2022-03-05, version 3.0.10* I don’t like how you can’t put a fraction in. Or the mode. That’s really it ### 5/5 — Solver has major problems *2022-02-17, version 3.0.10* Update: Developer’s comment that Solver uses TWO initial estimates cleared up some of the mystery. Referring to some high-quality (HP and true PDF, not scanned images) documentation cleared up some confusion about programming. A little serious thinking took care of the rest. So in fact Solver works as advertised. I offer my apologies for my part in the confusion; but not on behalf of some terribly confusing third party documentation. Excellent app. ************************************************** I really want to like this app. I really do. But the Solver keeps producing strange, unexplainable results. I have been using the quadratic equation x^2-5x+4 as a test case. At various times the Solver has worked correctly; returned the ‘Sign Reversal’ error message; found 7 as a root; found only the root x=1 regardless of the initial estimate; and found 6.03125 as a root. I am completely baffled as to how this can be happening. But I certainly can’t trust any results this app produces. ### 5/5 — ReVerse Polish Notation , the only wAy to go *2022-01-28, version 3.0.10* Between my 15c , numerous 48’s then the 42S in 1988, it was an easy decision to make. The programming was a bit arduous but once you were done you could print it out on your 82240 printer for line by line error checksum . Pole building calculations for non-fixed embedment became a breeze, retaining walls for ascending slopes not a problem. Now being retired it’s still my go to for Tig-welding art projects, taxes and sometimes checking the veracity of our leaders budget dreams. Thank You for a wonderful tool and please keep up the awesome updates Kws former G-man ### 5/5 — Great App *2021-11-07* Simply the best calculator app on the AppStore ### 5/5 — Great Calculator App!!! *2021-11-07* This is a great calculator app. For anyone that wants to do more than the basic mathematics, this calculator is ‘a must have’. RPN calculators are still the best and this recreation of the HP design is an incredible help for those of us that can’t buy this great product anywhere anymore. Thank you! ### 5/5 — Fantastic! *2021-07-15* What a wonderful surprise to find this. I’ve still got my original HP 42S but now I can use this one when I’m out and about. Thank you! ### 5/5 — outstanding—suggesting important use case *2021-07-02* The developer and many of the reviews do a great job of explaining just how well this emulation works. Teaching computer basics via this calculator is a great option: In the spirit of teaching machine language for a simple microprocessor, kids learning how this RPN calculator works would learn how numbers, stored in locations, are manipulated and stored. The basics of a logical test are there. In short: the kids would see the close analogues of the most elemental binary commands: shift left shift right add logical test and see how all programming has a very simple logical foundation. ## Most critical reviews (10 lowest-rated) ### 1/5 — Calculator *2023-07-18, version 3.0.20* I’ve had a HPC 12 for years, and it was very simplistic to work with. This calculator is very complex and not easy to use. Does it even come with an instruction manual? ### 1/5 — Calculator not correct *2019-12-22, version 2.5.11* 20 enter, .07, x, plus, gives 1.04 ? ### 1/5 — 150,000 x 0.1. =. 0 ???? *2018-05-05, version 2.0.20* 150,000 X 0.1 = 0 ???? ### 1/5 — doesn't download?? *2013-06-11* I twice selected this app for download but it never appears on my ipad... says it can be 'updated' via itunes, but I haven't got it... ### 2/5 — Mise à jour a revoir *2019-02-17* Depuis la dernière mise à jour, les skins ne sont plus affichés étirés sur tout l’écran. Résultat, avec un iPhone Xs Max, on est obligé d’avoir des calculatrices toutes riquiquis, pas du tout adaptées à la surface de l’écran. Yes, there is a skin that is adapted to the iPhone Xs but the new behavior of the application about the skins has the side effect that all the previous skins cannot be used anymore. Pleasd restore the previous behaviour **Developer response:** Skin sizing is fixed in 2.0.23c. ### 2/5 — Not full screen anymore *2019-02-14, version 2.0.23a* I love this app as it recreates my calculator of choice. Used it for many years. However, the latest update messed up the display. The calculator is not full screen anymore. It just fills about 60% of the screen. Please fix. ### 2/5 — Best design but last update not good *2014-08-02* Last update has modified the sensibility of the keys. Design better than others RPN calculators. Please optimize for iPhone5. ### 3/5 — Square root function not working *2024-06-26* Not sure why, but the square root function doesn’t seem to be working properly now. Was working okay before. Not sure if other functions are also impacted. Used to love this up until this happened **Developer response:** It sounds like you're in BASE mode. Press EXIT repeatedly until there is no menu in the display, that should get you back to normal. If that's not it, please contact me via email. It is a bit difficult to do tech support in review replies. ### 3/5 — Not bad *2016-04-08* Not a bad hp42s calculator. Graphics could be a bit cleaner. I'd use this app I'd it wasn't for the annoying key click which can't be turned off ### 3/5 — Nostalgie du monde HP ...:-)) *2010-10-16* Bonne idée ## Most praised reviews (10 highest-rated) ### 5/5 — THE best calculator app *2026-01-16* The HP42s is one of the best calculators ever made. I love Free42. Plus42 is even better, which I was happy to buy to support the development of both apps. ### 5/5 — One request *2025-10-27, version 3.3.9* Big fan from forever ago. Had free42 on all my PalmOS devices, Android, PC, and i0S since my IPhone 1. However, the current version on iOS has the oldest built-in skins instead of the newest ones. Please fix? ### 5/5 — Super *2025-08-23* Use a 42s on my desk since many years. Nice to have one with me all the time! Thank you very much! ### 5/5 — Works great *2025-01-30* Wish there was a 41 CV version to replace my real one. But this is a good replacement. **Developer response:** I'm glad you like Free42, but if you're specifically looking for an HP-41CV or CX emulator, i41CX is a good option. ### 5/5 — Would recommend *2024-12-19* This is an awesome RPN calculator, and does all the things you need and more. ### 5/5 — Best free app for thinking people *2024-11-20* This app is a service to mankind. Especially if you only speak RPN. ### 5/5 — Fantastic! *2024-08-29, version 3.1.8a* So nice to have this available. I have always been a diehard HP RPN calculator fan. This app is a faithful and convenient reproduction. ### 5/5 — RPN Rules *2024-03-30* My physical HP calculator died after 36 years and like many old engineers (I suspect), I wouldn’t use anything else. I tutor high school kids, with their TI 83’s and 84’s. Even though they can text much faster than me, an RPN calculator runs circles around them. This app is a perfect replica and I urge anyone who is allowed to use an iPhone to try it. It takes about 20 minutes to get used to a completely different way of operating, but you won’t ever go back to algebraic entry. ### 5/5 — Fantastic App! *2024-02-09* I have always used HP RPN calculators spanning a period of over fifty years and this App is a faultless rendition of the original calculator. One really niggling problem is that the screen has rotated 90 degrees to landscape. Trying to get it back to portrate does not work. Any ideas? Any fix coming? Ray Shead **Developer response:** Please contact me via email. ### 5/5 — Thank you, thank you!!! *2024-02-08, version 3.1.3* I’ve been using my hp42 since buying it the day it was in stock for sale. Its a one-owner! On back it says 1987 Made in USA. SERIAL No …A11141. I digress. Some of my keys have started to act up after 36 years of perfect service. Finding Free42 is a godsend! I’m running it on an iPhone SE. I re-entered some really old programs I’ve kept on my 42s and they work flawlessly. I am so grateful you’ve created this app. Thank you, thank you! --- *Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-16.*