# Plus42 — user reviews

> 39 indexed App Store user reviews of Plus42 by Thomas Okken, rated 4.90/5 from 79 ratings.

- Source: https://appshunter.io/ios/app/plus42/id1597963622/reviews
- App overview in markdown: https://appshunter.io/ios/app/plus42/id1597963622.md
- Rating breakdown: 5★ 76 · 4★ 1 · 3★ 0 · 2★ 0 · 1★ 2

## Newest reviews (15 of 39)

### 5/5 — Best RPN calculator out there

*2024-11-05, version 1.1.13*

Great implementation of the HP42. Would love it if the developer could add a dark mode icon.

### 5/5 — Love This

*2024-07-06*

In college I was an HP41C user. Once in my first engineering job I switched to the HP42S which has served me well over my 30+ year career. Once iPhones became a thing, I loaded Thomas’s Free42 and have been using that for a couple decades. I still have a real 42S on my desk for daily use. I recently purchased an HP Prime which is a lovely calculator but it’s just not completely comfortable to use. Switching to Thomas’s Plus42 feels really comfortable and adds lots of lovely features.  I will likely purchase a SwissMicro DM42 to be used as my daily desk calc so that my phone app and physical desk calc are similar. That would send the 42S to the vintage calc cabinet. Honestly having this on my phone is massively so functional it’s hard to justify even owning a physical calc but there are times at the desk when it’s nice to grab the physical unit with tactile keys that can’t be interrupted with alerts :-). This is a beautiful upgrade to the free42. Thanks Thomas!

### 5/5 — The best by far

*2024-03-27*

This calculator is the main I use. It's a great scientific HP-like calculator inspired on the 42 model. Its fast, efficient and above all maintained and improved.
When I need to do anything, I use this one first.
I love its precision.
I deleted the Apple one because this one is better by far. You can't go wrong with this one.

### 5/5 — 非常好的模拟器，如果能支持iOS 9就更好了

*2024-03-14*

App功能非常强大，如果能支持低版本的iOS就更好了，比如iOS 9.3 ，这样就可以在一些老的iPad，或者iPhone上安装它。
希望开发者能认真考虑一下这个建议。

**Developer response:** Unfortunately, Apple's current software development tools only support iOS 12 or later.

### 5/5 — 全てに驚愕!plus

*2024-02-01*

DM42とあせて使っています。
ボタンの光沢輝きをfree42なみにしていただけたら、私には、もう完璧だと思います。
πの1万桁を約1. 5分で計算してくれます。
このアプリには虜になってしまいました。
日本語取説が欲しいですが、それは贅沢な要望かも知れませんね！
開発者さん、有難う❕

### 5/5 — Excellent calculator !

*2023-12-04*

As old user of a HP42 and actual user of a Swissmicros DM42, iI use Plus42t every day and appreciate it very much !
It is the best calculator i ever had

### 5/5 — Beautiful and functional at the same time

*2023-10-17*

Thomas has done an outstanding job on this app! It is not only the most beautiful calculator app out there, but it’s also the most powerful and functional of any of the HP inspired calculator app. The graphics are outstanding and the “extras” that were added in addition to the 42s standard makes the app even more appealing.

If you know how to use a RPN calculator, this IS the one to have and use. If you don’t know how to use a RPN calculator, learn how and buy this.

I always carry my phone, but rarely my physical DM42  or “real” 42s.

You won’t regret getting this app.

Congratulations Thomas for all the work you have done over the years relating to the 42. You should be proud.

### 5/5 — Perfect!!

*2023-10-11*

I use this calculator over all others. It has great precision and is easy to use, yet is powerfull. It is very well made. I couldn't find any bug or design defect. It's a very well thought app.

### 5/5 — Einfach der perfekte Taschenrechner

*2022-12-31*

Auf meinem Schreibtisch liegen seit 30 Jahren Taschenrechner von HP. Am häufigsten nutze ich den HP 32Sii. Mit dem Plus42 muss ich auch unterwegs nicht auf den Komfort eines RPN-Taschenrechners verzichten, sondern habe ihn allzeit griffbereit dabei.

Mittlerweile hole ich sogar im Büro den physischen HP Rechner kaum noch aus der Schublade, weil die App mindestens genauso gut ist.

### 5/5 — Der letzte Taschenrechner! Der totale Hammer! Killer-App! :-)))

*2022-12-05*

Als Luft- und Raumfahrtingenieur habe ich eigentlich keine Zeit Bewertungen abzugeben. Hier muss(!) ich aber mal eine Ausnahme machen.
Thomas Okken hat mit dem Plus42 meine fast 50-jährige Suche nach dem(!) Ingenieur-Taschenrechner für den Maschinenbau beendet. Die App ist der totale Hammer! Jede Ing.-wichtige Taste ist jetzt bei mir auf der obersten Ebene! Keine(!) Umschalttaste mehr! Dann noch UPN bzw. RPN, mehr geht nicht. In Sachen Geschwindigkeit zieht der Inhaber der App damit allen davon! Ferner gibt es den noch für alle Plattformen und auch als Desktop-Version! Die Programme können auch noch getauscht werden!
Der Rechner erweitert den DM42 von SwissMicros für 200 CHF sogar noch um 6 Tasten! Der Rechner und das ist der Hammer, arbeitet mit 128 Bit Genauigkeit! D. h. Exponenten von -6143 bis +6144 sind somit kein Problem mehr. Einfach mal die Fakultät von 70 berechnen lassen: 70! und die meisten Taschenrechner melden sich dann ab. Nicht aber der Plus42, der hält, was er verspricht! Absolute Kaufempfehlung von mir für Ingenieure!
Thomas, Peta-Dank, was für ein Job! :-))))))))))))))

### 5/5 — The best calculator-computer period

*2022-11-21*

With some programming, this can replace both of my units conversion and finance calculators apps. It is that powerful. I hope - and still have not figured out - we could use and call the TVM variables (PMT, FV, etc) in our custom programs, rather than duplicate the already available functions.

**Developer response:** Yes, you can use the TVM functions in programs. Use STO "N", STO "I%YR", etc., to set the known parameters, and then use the N, I%YR, etc. functions to calculate the unknowns. Note that all of N, I%YR, PV, PMT, FV, BEGIN, and P/YR must be set, or you'll get a Nonexistent error. (The value being calculated does not have to be set in advance; its value is ignored.)

### 5/5 — Better than the original HP42S

*2022-10-02, version 1.0.11*

I purchased this HP42 emulator today.  I am a long-time fan of HP calculators and a keep collector of both HP and SwissMicro products.  This is the same form factor, but an improved version of the SwissMicro 42S calculator, which is also based on the free version of this emulator.  Love the SwissMicro calc, and love this iOS calc.   Well done Thomas Okken.  Great work.  This one is a keeper, and well worth the money.  Five stars!

### 5/5 — Solid well implemented RPN calculator

*2022-09-15, version 1.0.10*

This calculator is the one I use first. It's powerfull, excellently done and works allways as expected. Also, it's well maintained. I wish all apps were made with this quality level.

### 5/5 — Fantastic

*2022-06-13, version 1.0.7*

I have a real HP 42S and this is a great choice for an iPhone calculator. It does everything the 42S does and more. I like the different screen displays and the haptic feedback. My favourite iPhone calculator so far!

### 5/5 — Best Programmable Calculator

*2022-05-31*

Have been using Free42 for years but Plus42 is Free42 on steroids. The new features like Dir and Eqn are great enhancements. Many thanks for to this developer for all his efforts.

## Most critical reviews (10 lowest-rated)

### 1/5 — Not worth of it

*2026-05-09*

Don’t waste your money!

### 2/5 — Can’t convert from DMS to decimal degrees!

*2026-01-09, version 1.3.12*

WTF. It can easily convert decimal degrees to DMS, but not DMS to decimal degrees?!? What is the point of having one but not the other?!?

### 3/5 — Can’t import programs

*2023-06-12*

No files or directory can be seen with the Files App as Free42. How can I copy programs from Free42 to Plus42 and import them? And the author’s website can’t be accessed.

**Developer response:** https://thomasokken.com/free42/#load-save
Sorry for the slow reply, I never got the notification about your question. Note that reviews aren't a good place for asking questions; it is much more convenient to contact the author using email. Thanks!

### 4/5 — why does  this calculator can only store 4 numbers?

*2024-06-14*

Hope can store more numbers

**Developer response:** You can store as many numbers as you like using STO. Or, if you want more than 4 stack levels, you can use the dynamic stack, by switching to NSTK mode: MODES ▲ NSTK. (You can return to the 4-level stack mode with MODES ▲ 4STK.)

### 4/5 — Need multitasking

*2024-01-27*

When using on iPad, the app occupies the whole screen. Currently it does not support multitasking. But it would great to share the screen with other apps (side or floating window).

**Developer response:** I added iPad support in 1.1.4a.

### 5/5 — Plus42 fanatic simulator

*2026-07-19*

This is a fantastic HP-42S simulator. Very functional, I use it daily. My HP calculator has long been dead and this allows me to use an RPN scientific calculator in daily engineering tasks. Thank you.

### 5/5 — Best calculator app!

*2026-01-15, version 1.3.13*

I *LOVE* Free42
Plus42 is even better!

### 5/5 — Perfection

*2026-01-12*

Once you use an RPN calculator, you will never go back. The HP-42S beats the HP Prime in layout and ease of use for most task, and the enhancements in this implementation is great. I love having the (enhanced) HP-42S always with me on my iPhone whenever I need a calculator.

### 5/5 — Great calculator, however

*2025-12-24*

I’ve really like this calculator however lately there seems to be an issue with programming. I had a program for the sulfur to convert Celsius to Fahrenheit and vice versa but for some reason it doesn’t work anymore so 212 Fahrenheit should be 100 Celsius. it comes up with something like minus one point something to the power of 6000 I wonder what the issue is?

**Developer response:** Please contact me via email for support.

### 5/5 — The Perfect Calculator

*2025-10-28*

The 42s was, in my opinion, the most elegant calculator ever devised during the golden age of HP engineering.

This simulator perfectly recreates this legendary calculator and it adds some additional great features. It has several enhancements seen in the RPL calculators without introducing the shortcomings of the more complex interface. Put another way, this calculator is what HP should have done with the 48 line.

I believe that Plus42 now deserves the crown of the best calculator. It is the perfect continuation of the RPN days, and since it lives on your phone, it is always at hand. All that for just under $10!

## Most praised reviews (5 highest-rated)

### 5/5 — Wow

*2025-10-01*

Can’t believe how happy this app makes me, to once again have my favorite calculator in hand. The HP-42S was unmatched and this app replicates it perfectly. Simply amazing. Thank you!

### 5/5 — Super Implementierung

*2025-06-08*

Ich nutze den Rechner jetzt schon seit längerem (in der Plus-Version). Bin sehr begeistert, echt super!!! Auch das Programmieren funktioniert „wie gewohnt“ (wie früher), echt cool, danke!

### 5/5 — What a delight!

*2025-02-28*

I can’t believe I missed Thomas Okken’s free42 and plus42 projects until now, over 20 years after his first release it appears.  It’s been a joy to get reacquainted with RPN and now have the same calculator on my phone, which I have on me all the time, as I have at my desk in physical form via SwissMicros’ DM42n that just arrived. Having a physical calculator at my fingertips that I love to use is something I haven’t experienced in probably 30 years, since college. The astro navigation and conversion  apps I pulled down and loaded from Thomas’ website this morning is what prompted me to write this review.  Thank you Thomas for this gift to us all!  You’ve left no detail out for someone like me.

### 5/5 — Best calculator I've seen

*2024-12-19*

I tried several calculators apps and in my opinion this one is the best by far. It has much more than I need and yet it is easy to use and intuitive. This is the one I use most.

### 5/5 — 希望在矩阵计算的功能更多一些

*2024-12-01*

类似50g，在矩阵的创建、运算、分解支持更多功能
。
比如可以直接提取某一行列为对角矩阵，
50g的矩阵计算功能十分丰富，如果像plus42这样支持大屏幕，会极其美好

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*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 2026-09-01.*