# 15C Pro Scientific Calculator — user reviews > 171 indexed App Store user reviews of 15C Pro Scientific Calculator by Vicinno Soft LLC, rated 3.80/5 from 281 ratings. - Source: https://appshunter.io/ios/app/15c-pro-scientific-calculator/id421102285/reviews - App overview in markdown: https://appshunter.io/ios/app/15c-pro-scientific-calculator/id421102285.md - Rating breakdown: 5★ 161 · 4★ 38 · 3★ 10 · 2★ 4 · 1★ 68 ## What do users think of 15C Pro Scientific Calculator? Overall sentiment: negative **Pros** - 🚀 Faithful emulation of original HP-15C - 👍 Works just like the real calculator - 💡 Convenient to have on phone - 🚀 Accurate calculations - 👍 Familiar RPN interface **Cons** - 🐛 Crashes on iOS 13 and later - 🐛 Orientation issues on some devices - 🐛 Occasional locking up - 🐛 Display issues in portrait mode - ⚠️ No longer maintained or updated **Commonly reported bugs** - Crashes on launch with iOS 13+ - Displays only half the calculator in portrait mode - Locking up when accessing the help screen **Most requested features** - Add haptic feedback on key presses - Implement program storage and retrieval - Add support for latest iOS versions ## Newest reviews (17 of 171) ### 2/5 — Used to be great, but now terribly slow *2025-07-31, version 2.3* Slower than 1987 real calculator, how possible ### 3/5 — Not functional *2024-10-18* I have an iPhone 16. With the phone position sideways the calculator works excellent. My rotate vertical the image does not rotate. Also, there’s no access to settings as shown in the pictures. Lastly, it’s very difficult to close the app to move to something else. The normal swipe doesn’t work. ### 5/5 — Works exactly like my hardware 15C *2021-11-26* This is a great app that works like my hardware version. I used the 15C long before this app existed but find I now log more time on this iPad version. I recommend this app without hesitation. ### 5/5 — my HP 15C version of choice *2021-07-12* there are a few HP-15C calculators available on the App Store. Most of them commercial version that cost money. Vicinno Soft's is free and BY FAR the best one I've tested. And free. What else can you ask for? The only drawback is the iPad version, which has the problem that it needs to be started while the iPad is in a vertical position. It will start "sideways", and the iPad can be rotated then, all good. But if the iPad is rotated first, and the app started then, it shows up only as a half. It detects the orientation of the iPad at start, and then behaves as if it was running on an iPhone. Although the iPad has enough real estate to show the full calculator in any position. But that is only a minor annoyance, and since the calculator is free, nothing to complain about. Thank you, Vicinno Soft, for the great product! ### 5/5 — Wonderful *2021-04-28, version 2.3* Inverse Polish notation is far faster way to do calculations. A perfect alternative to using my genuine HP15C from the late eighties ### 5/5 — HP15C *2021-01-29, version 2.3* Found this app and bought immediately. I felt like I found an old friend. Best machine ever for engineering calcs ### 5/5 — Works Great...Control Center Coming? *2020-12-03, version 2.3* Now my iPhone is complete! Now if I could only add it to the Control Center life world peace would be achieved! ### 5/5 — Best 15C app out there *2020-11-01* As well as being affordable, this app seems to properly save the state of the calculator, including programs and registers, when the program is stopped or the IPhone rebooted. The free app and HP’s overpriced official version do not, a disqualifying flaw. Who wants to re-enter their programs whenever their device reboots? No flashing display after running a program, a silly uncorrected bug in HP’s app. Plus, this one has a well-done portrait mode and an excellent help that includes the full manual. The key clicks sound good and are switchable from within the app. Haptic feedback capability would be nice. Programs seem to run somewhat slower, but that may be eye candy so the “running” display can be displayed for a second or two during program execution. Feels much like the original. Love it. ### 4/5 — Maybe add Haptic *2020-10-08, version 2.3* I really like this calculator. It would be nice to have haptic feedback upon key press. This would help knowing that a number is pressed and not double pressed ### 5/5 — Top ! Une HP15C dans la poche *2020-09-29* Les calculatrice en notation pol. inversée sont rares. C’est très utile de retrouver ses réflexes d’antan avec cette appli. utilisable pendant les déplacements, la vraie reste au bureau ! ### 4/5 — Please add Programs Storage/Retrieval *2020-08-18* This is the best HP 15C emulator. Behaves and feels just like the real one. Anyhow, taking advantage this is an emulator and considering the original 15C could not store/save programs (i.e. you have to retype a full program each time you switch programs)l, PLEASE add programs storage/retrieval capability! This is a must. ### 5/5 — Either I use this one or the real 15C *2020-08-10* This app is great works just as expected. I love my HP 15Cs. Started using the 15 see you about 25 years ago. I still have it and often use it. The nice thing about this app is I have my 15 C wherever I go. I’m so glad they created this app ### 4/5 — HP 15C *2020-08-07, version 2.3* Very satisfied, just wish I had the real calculator for my collection. ### 5/5 — Works for me *2020-07-09, version 2.3* As is the case with many others, I switched because my old 15C emulator stopped working after an iOS upgrade. This one works for me just fine. I’m very grateful to the developer for keeping the 15C alive. ### 5/5 — HP 15C *2020-05-17, version 2.3* Works like the original. ### 5/5 — Great App! *2020-05-17, version 2.3* I so missed this app when IOS was upgraded a year or more ago. So glad you have now fixed the “bug” as it now runs beautifully again! It almost feels like my favorite calculator did all those years ago! Thanks again! Highly recommended. ### 5/5 — Finally fixed bugs *2020-05-15* Didn’t work for iPhone X. So annoying. Finally fixed the bug and working great now. Thank you for updating. I was despairing that it would never be fixed after silence for nearly 3 years. ## Most critical reviews (10 lowest-rated) ### 1/5 — Not worth it *2026-06-08, version 2.3* Just purchased this app. It has an obnoxious clicking sound when pressing any button, and it cannot be turned off. Will be seeking refund. ### 1/5 — Moins bien qu’une autre application *2025-05-29* J’avais l’application touch 11i. Bien mieux. Malheureusement d’un seul coup elle a arrêté de fonctionner. Celle application fonctionne mais pas très agréable. Impossible de la mettre verticale. De paramétrer le bruit des touches …. ### 1/5 — Versio 2.3 did not fix the bugs in 2.0 *2022-03-17, version 2.3* It seems that Viccino stopped maintaining this paid app. A real shame. The problems in version 2.0 are still present in 2.3: rotation problems, no settings, no back page and display half calculator when in portrait mode. Please try again. I used to love this calculator. ### 1/5 — 11-Apr-20: Latest patch didn’t fix it *2020-04-12, version 2.0* 11-Apr-20: Latest patch didn’t fix it. Current problem: Begins with just half a calculator - in portrait mode. Switch to “menu” screen appears to bring up the calculator, but accessing the “help” screen, calculator totally locks up, can’t get rid of “help” screen. Bottom line: Still not working. 29-Dec-19: Add my name to the others who have complained that the app stopped working for iOS 13. As of the December update, app wouldn’t work at all. ### 1/5 — Was perfect no longer works on iPad *2020-04-07, version 1.89* Please update this app, maybe add a bigs reel feature to iPad. Even if no features are added as long as it works again I will change rating to a 5. ### 1/5 — Calculator *2020-04-06, version 1.89* It does’nt work with iOS 13...please update App completly unstable ### 1/5 — An emulation of a 15c, crashed immediately *2020-04-01, version 1.89* This was, WAS, a great application. It crashed immediately after opening. I’ll rate it 5 stars once again if it stays open and useable. Still love it. Works just like a 15c Btw for the other reviewer, RPN calculators don't have an "=" button, they don't need it. Nice calculator works just like a HP. ### 1/5 — William Dudley *2020-03-25, version 1.89* Downloaded the. 11C and 15c. Neither will open on my iPhone 10 pro. What’s up !! Thanks Bill ### 1/5 — Does not work anymore *2020-03-23, version 1.89* I have had this app for several years but it does not operate with new iOS. ### 1/5 — It’s dead, Jim *2020-03-20, version 1.89* Sad to see it go ## Most praised reviews (10 highest-rated) ### 5/5 — Excellent App and Sci Calc *2024-02-17, version 2.3* This is an excellent app and HP 15C Scientific Calculator. I teach AP Calculus BC, and I use it often for my calculations. The user interface is clear and accurate, and the calculations are accurate. Highly recommended. ### 5/5 — App essentielle *2023-11-22* La meilleure app, simulant l’une des meilleures calculatrices scientifiques HP. Je l’utilise au quotidien, en remplacement de ma 15C, quand je ne l’ai pas sous la main. Un très beau boulot, en tous points conforme à l’original. ### 5/5 — Great Tool *2023-02-09, version 2.3* Works just as good as the original. And as long as I have my phone it is with me and ready to go! ### 5/5 — Reliable through four years of use *2022-12-27, version 2.3* Same as college days. Reverse Polish notation is the best. If you loved the device, this app is for you. ### 5/5 — Mr. Luizon *2022-10-08* Outstanding ### 5/5 — Stuck in RAD? *2022-05-30, version 2.3* g DEG 60 COS I get -.95, the RAD answer. But RAD is not on the display. What am I doing wrong? How do I get to degrees? g DEG does not seem to work. This is my only known question on my beloved 15C app. Thank you!! ### 5/5 — Just like college *2022-04-28, version 2.3* The HP 15C got me through four years of computer science, physics and electrical engineering. This is the same and it’s programmable just like the 15C. Cool beans. ### 5/5 — My 11C finally crashed *2022-04-05, version 2.3* I’m so relieved that I can now have my scientific reverse Polish calculator on my phone. So far I’ve not found any problems, it seems familiar like the physical version and I’m very happy. ### 5/5 — Works like the old fashioned RPN calc *2022-02-08, version 2.3* It even has the sound like an hp calc when you press the keys. Well executed app. ### 5/5 — Great APp *2022-01-08* Für alle, die die alten HPs lieben: eine tolle App, die das iPhone in einen richtigen Taschenrechner wandelt! --- *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 2026-09-02.*