Free42

Great app, if I could give it 6 stars I would. Very good emulation of the HP 42, with some extra added features that make it even better. And I *love* the 34 digits accuracy! It lets me solve problems that are beyond the capabilities of any other calculator I've used.

I learned to use a calculator on a HP RPN and this is a perfect replica. This is a must have app for me as I can't use the default calculator.

My HP11 runs out of battery every 15 years. The phone only lasts a few days.... I'm going to be buried with the HP and spare batteries. But this app normally allows me to leave the HP safely in its cover. It is superb. The display even simulates the key shape.

This is unquestionably a great app. If I had to offer any criticism it would be regarding the font chosen for the display. It does mimic the one used in the original HP42, but it would be very cool if we could choose more readable fonts and/or font size (yes, I have tried the Display Smoothing option). Incidentally, the real-world version of the DM42 (skin available at the app developer's site) also mimics the HP42 but uses a much more readable font. Also, when using the SwissMicros DM42 skin & layout files, the added top row keys don't follow the real calculator functions. On the real device they control font size, call menus, etc. It seems that on this skin they are merely repeating the standard top row keys (XEQ, LN, LOG, etc).

This is by far the best calculator available anywhere, is even superior to the original HP version. It makes keystroke programming of complicated programs as simple as for quick short tasks. Unlike HP42S, Free42 uses 34-digit accuracy in all its internal functions (eg. up to 35! is a machine integer), including complex-valued matrices. Because it can also display its full 34-digit internal precision (unlike HP42S which is 12 digits), this calculator can be used for legal financial tasks. The developer made it easy to save/load programs and printer output via plain text files. Performance is very fast on my low-end Snapdragon 425 CPU. I verified many functions at random from the HP-42S Owner's Manual, and they all work as expected. UI view changes to HP landscape style when you rotate your phone, making aficionados of either style happy. If you haven't tried RPN yet for chain calculations, you'll be hooked. Kudos to the developer and contributors for such an ergonomic handy UI implementation and functional design. 5.0 stars.

I still have two HP42s, one for my office at work, one for my office at home, both in a drawer. Free42 now resides on my phone and computers. It is a perfect emulation with some significant advantages in stack height and memory. I occasionally miss the HP's programmability, but usually just turn to a spread sheet for highly repetitive calculations or more specialized apps or programs for more challenging work.

For a calculator app that optimizes keystrokes, this is the one. For the classic HP calculator experience in an app, start here. If you want an RPN calculator, you won't find a consistent, faster, smaller, scientific, featured calculator cheaper. If you want graphing or algebraic or textbook entry, keep looking.

Great to have a nice RPN calculator with me when I don't have my HP 32S II along. I like the 2-line display that shows both X and Y registers.

My favorite calc to date (still have a special place for the 41 emulator), gotta love 34 decimal accuracy. Nice extra features!!!

Absolutely wonderful work. I prefer one of my real HP calculators, but sometimes all I have with me is my phone. I've used several RPN calculator apps, and this is one of my two favorites. For a phone app, giant graphing calculators are unwieldy. On a phone screen, the keypad of the 42S is very manageable. A joy to use.

This is just like the HP-42S I used to own! Except it has more memory, is much faster, and always there on my phone. Oh and did I mention the built-in printer with virtual paper, and the ability to save my work as a file? My college calculator would be envious!

This is the coolest gadget going! I never owned an HP. I was surprised to find that this simply-designed version came later (1988). I can imagine that programming it was for those with plenty of patience! ;) But, IMO, its minimalism makes it the nicest if the HP series.

Very good and complete RPN calculator. Would be even better if the app contained a low-resolution and a high-resolution picture of the calculator, and automatically chose which one to use.

I like it quite a lot. Don't know if I can write functions anymore or if it's possible. I can automatically input values from a formula and get correct results. Unlike me trying to use an algebraic calculator and mess up the process. So for me Free42 works well.

The Free42 app turns my Android phone into a convincing full-featured replica of the Hewlett-Packard 42S calculator. My (real) HP42S was a trusted tool during many years of college, plus a decade of professional use. The Free42 app works just like the 42S, and is always there on my phone when I need it.

Ive used this app for years. Its the greatest calculator app I have ever used. I love the RPN design of the original HP, the programmability and the memory. I download a new copy every time I get a new device, then load all the programs I wrote for my original HP 42s 30 years ago. It never crashes and no update has ever made it misbehave. This is the only app I can say this about.

That this app exists makes me very, very glad. I am so thankful to Thomas for developing and especially for sharing this with the world, for free! Before phone apps, I used this on my Linux and MacOS desktops for years. Now that I have it on my phone, I recently sold my collectable HP42S for about $400 (!) and used some of the proceeds to make a donation to Thomas through his website. Worth every penny. A perfect emulation of the original device.

Unbelievable simulation of the best programming calculator ever. The developer is extremely active too, updating the app very often, making it more and more powerful. Can't live without it! It's my "go-to" calculator.

This is a perfect copy of the best calculator (IMO) ever made. It's free and there are no ads. I use it constantly and I can't think of any faults or ways to improve it. Truly 5 stars!

I've been using Free42 on my desktop for years and just got around to adding it to my new phone. It can even used the custom skin I made in Windows. I also sideloaded a copy onto my 7 year old Galaxy Prevail just so I can always have a standalone Free42 calculator. What a great use for the old girl.

I really like this app but the skin function seems to not work at all on my phone. It allows me to select one, but doesn't actually apply it. If this is fixed it will definitely be 5 stars.

GUI changed radically! Like when M$ introduced the idiotic "ribbon" GUI. I was a long-time HP calc user, and one thing that appealed to me about this app was the familiar look & feel. Now it's gone -- bad move by developer, I'm ditching it & trying out alternatives.

On my Samsung I held the bottom right button to get the menu, with the latest version I long tap the lcd display area for the menu...This should be noted per instructions. lucky I discovered it on my own.

This is staggeringly amazing. I cannot say enough how amazing it is that this doesn't have ads. That would completely destroy the aesthetic and the developer seems to get that. Hopefully there is a way we can donate to support development!

Excellent android version of my good old hp42s. Only negative point, the graphical does not match my screens resolution. It looks a bit stretced (samsung s20 fe) Updated 4/4-2021 Selecting another skin solved the problem. In this case ovens42large matched the phones display perfectly

Simply brilliant! I loved the 42 and RPN. I Just wish HP would manufacture these and the 48SXs again exactly as they did back in the 80s. Highest quality calculators ever created by humans. They were my go-to calculators. Thanks so much for resurrecting them as software so that they will exist forever!! Job extremely well done.

RPN scientific calculators are easier to use, even for simple repetitive algebraic calculations.