# Retro 15C — user reviews > 113 indexed App Store user reviews of Retro 15C by Greg Hewgill, rated 4.30/5 from 212 ratings. - Source: https://appshunter.io/ios/app/retro-15c/id583559000/reviews - App overview in markdown: https://appshunter.io/ios/app/retro-15c/id583559000.md - Rating breakdown: 5★ 157 · 4★ 12 · 3★ 15 · 2★ 8 · 1★ 20 ## What do users think of Retro 15C? Overall sentiment: positive **Pros** - 🚀 Lightning-fast calculator - 👍 Authentic look and feel of HP 15C - 🚀 Faster than real HP 15C - 👍 Excellent RPN emulation - 👍 Familiar interface for HP 15C users - 👍 Great representation of original calculator - 👍 Obvious labor of love by developer **Cons** - 🐛 Doesn't save settings, programs, or memory - 🐛 No key press feedback or sound - 🐛 Blinking display issue with large calculations - 🐛 Bugs with HMS conversions - 🐛 Can't close app on newer iPhones **Commonly reported bugs** - Blinking display with large calculations - Bugs with HMS conversions - Inability to close app on newer iPhones - Stopped working with iOS 14 updates **Most requested features** - Add haptic feedback on key presses - Implement continuous memory to save settings and programs - Add portrait mode option - Improve compatibility with newer iOS versions - Add copy/paste functionality for stack and registers ## Newest reviews (17 of 113) ### 4/5 — iPhone 17 *2026-03-17, version 1.1* It’s apparently not possible to close the screen, or close the app on the iPhone 27, which has virtual handles on the screen corners. You must turn off the screen and then switch. Thanks for your support. I hope you can fix this, as I have enjoyed the app for many years. ### 3/5 — Good, but no way out *2025-08-25, version 1.1* As far as a HP11, it’s fine. But, there is no exit button, half swipe up app switcher fails also ### 5/5 — I use it every day *2024-03-23, version 1.1* I love this app. One minor issue is that with the loss of the home button, it’s not so easy to close the app. It’s hard to get the skinny bar to turn white. I’d also like a click sound when I touch a key. ### 5/5 — Excellent for a free RPN HP-15C calc *2024-02-07, version 1.1* This is still my default calc in my iPhone. I even deleted the iOS calc !!!! ### 5/5 — Way back machine to college days *2023-11-11, version 1.1* I absolutely love this calculator! I started with a 25c for electronics. I now have an 11c and a 16c. This is my favorite go to calculator now. It is perfect for RPN users. Love it, love it, love it! ### 2/5 — App will not close- iOS 17.0.3 *2023-10-17, version 1.1* Been using this app for years, you could always close it by swiping it off the screen. Once it’s on an iPhone with no Home button, you can’t exit the app. The only way to exit the app and get back to the icons is a hard off (power + volume up button) ### 5/5 — Thank you for this great emulation! *2023-10-10, version 1.1* I have loved the HP-15c since university. Once I got used to RPN style calculators, I never wanted to go back. You can easily calculate equations without fooling around with parentheses, storing and recalling intermediate values, etc. I still have my working HP-15c , but this tool lets me leave it at home and still use my calculator of choice wherever I go. Thank you, again! ### 5/5 — Great app *2023-09-13, version 1.1* Needed a calculator in a pinch and found this. Having used the 15c from way back I was impressed at how well this is done. Thank you ### 5/5 — Realistic implementation, just needs stick on tactile keys *2023-09-11, version 1.1* Definitely spooky, as real as it gets, even the programing works. ### 5/5 — Top notch emulator! *2023-05-31, version 1.1* Very nice emulator! Dev: how about copy/paste? And not just x. The stack and registers would be good. ### 5/5 — Amazing emulator *2023-04-30, version 1.1* This simulator is extremely accurate. Are used HP 15 C for the best 35 years. It’s one of my favorite HP calculators that I owned. Thanks for make it available on my iPhone ### 5/5 — Extremely well done *2023-02-28, version 1.1* I use this all the time and find it an apt replacement. Saying it is an excellent mimic seems much less the complement than I intend. Well done. ### 4/5 — Great Emulation, BUT… *2022-11-09, version 1.1* This program works great, except, the current version (9-Nov-22) has TWO bugs! The keys, STO and RCL are non-functional! This disqualifies the ability to save results in the storage registers. PLEASE FIX,!! ### 4/5 — Buggy HMS conversion *2022-11-08, version 1.1* This app is my on-the-go 15C. Overall, it’s excellent. I wish the developers would fix the HMS conversion bug reported by others. 5h30m -> 5.5111…h??? ### 5/5 — All-time favorite calculator *2022-10-05, version 1.1* Bravo to this developer! This was my favorite calculator of all time. On my iPhone 11 Pro Max, I am transported back to 1980. Not to name any names but it’s been downhill since then. ### 3/5 — Great 15C emulation, but….. *2022-07-31, version 1.1* First off this app is great. Perfect emulation of the 15C and on modern iPhones it’s actually faster than a real 15C. But there is one significant issue. It does not play nice on newer iPhones that don’t have a Home button. Specifically, once the app is running, there is no way to go back to Home screen or turn off the app. On an i13, the up swipe does not work. You have to press the side button then swipe to a notification to get out of the app. Real PITA. Please fix this. I’d give 5 stars but since this problem is significant, I’m only giving 3. ### 5/5 — How did I never come across this before? *2022-06-20, version 1.1* I love my HP15C. I bought it used almost 40 years ago and still use it today. Conversely, every calculator app I’ve tried I’ve hated. I would rather toss my phone aside and grab my physical 15C. Now I no longer have to. I now have a 15C with me wherever I go. Thank you Greg! ## Most critical reviews (10 lowest-rated) ### 1/5 — Bad app *2025-11-04, version 1.1* Locks my iPhone in landscape mode, next to impossible to exit app ### 1/5 — Garbage *2023-07-21, version 1.1* The interface is like a fuzzy JPEG. ### 1/5 — No audio or visual feedback when touching any of the keys. *2022-06-24, version 1.1* Needs audio and visual key pressing feedback. Needs a better and cleaner looking HP 15C photo with higher resolution. ### 1/5 — Can’t exit out of app?? *2022-04-18, version 1.1* Had my phone hostage until I noticed I could get to settings from the Lock Screen. Deleted app. ### 1/5 — I Know Better *2021-07-13, version 1.1* Decimal degrees of 30’ is not .51111. ### 1/5 — WONT WORK ON IPAD PRO 11 *2021-04-08, version 1.1* It no longer works on my iPad Pro 11 2018 ### 1/5 — No longer works? *2021-03-10, version 1.1* I used to love this App but tried to run it today and it starts to open then closes. Are you going to fix it? I’m on iOS 14.4 ### 1/5 — Abandoned *2021-03-07, version 1.1* No updates for 3 years — pathetic. I loved this app when it worked. ### 1/5 — Not compatible with iOS 14 *2021-02-09, version 1.1* Love, past tense, this app! iOS 14 broke it and I would strongly recommend you’re not spend your money on it! ### 1/5 — Degree conversion *2020-05-21, version 1.1* There is an error converting some D.MS to H. Converting D.MS 2.3 - 8.3, 32.3 - 90.3 to H returns a decimal portion of .5111 when it should be .5000. I did not continue checking beyond 90.3 to see if this error continues. It seems to be only when converting 1/2 degree ## Most praised reviews (10 highest-rated) ### 5/5 — Outstanding program *2026-06-23, version 1.1* The designers/coders sweat the details. The appearance of the calculator is identical to the physical calculator. Excellent work !!! ### 5/5 — An old friend *2025-09-05, version 1.1* I was delighted to find this. I still own, and use, both 40 year old 15C and 12C calculators I acquired working at the HP IC fab that made chips for them. Thanks for bringing the 15C to my iPhone! ### 5/5 — Just the best thing! *2025-02-06, version 1.1* Appreciate the work to keep the app current. ### 5/5 — Engineering must *2024-10-31, version 1.1* I’ve been using this for many years in my work. Love it. Except, this week, the entire screen started to blink. Is there a fix? ### 5/5 — Fantastic *2024-10-05, version 1.1* If you know, you know… ### 5/5 — An Old Friend now on my phone *2024-09-16, version 1.1* Near perfection. The only thing I wish they would do is to add haptic feedback on the keyboard. Well done , guys. ### 5/5 — Still working on iOS 18 *2024-09-16, version 1.1* Just like the original calculator that I used as I got my PhD in physics. The best by HP. ### 5/5 — My go to calculator for years *2024-06-18, version 1.1* After a few bumps with the loss of a home button, this is back. Thank goodness! ### 5/5 — Awesome *2024-06-17, version 1.1* I use it almost daily at work, and it always gives me pleasure to see that 15C image! ### 5/5 — Still works in 2024! *2024-04-18, version 1.1* Good job future-proofing the app! --- *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 2026-09-08.*