# 12Calc — user reviews > 196 indexed App Store user reviews of 12Calc by Ernest Brock, rated 4.90/5 from 916 ratings. - Source: https://appshunter.io/ios/app/12calc/id780780002/reviews - App overview in markdown: https://appshunter.io/ios/app/12calc/id780780002.md - Rating breakdown: 5★ 842 · 4★ 58 · 3★ 10 · 2★ 4 · 1★ 2 ## Newest reviews (19 of 196) ### 5/5 — The Best! *2025-12-30, version 3.0* I have been using this app for many years and it has been accurate and dependable every single time!! ### 5/5 — 12C *2025-12-10, version 3.0* Great 12C ### 5/5 — Best calc app *2025-11-24, version 3.0* I love this calc. ### 5/5 — Better than the actual 12C *2025-11-15, version 3.0* I’ve been using a 12C in my real estate appraisal business for 30 years. This app is outstanding. Don’t hesitate to install it. It functions identically to the actual calculator only better. ### 5/5 — Mr maths *2025-10-29, version 3.0* The calculator is very efficient and useful for our daily business uses ### 5/5 — Better than ever - HP12C, only WAY Better *2025-10-28, version 3.0* This is my update on the best 12C option in the App Store. Why? You can use the HELP section to learn how to use an HP 12C! Tje programmers that created the original HP12C know this programmer too. You get pre-designed worksheets in the App to make the 12C much easier and useful. AND you can send results straight to your printer! Use it for your customer, like the amortization tables just to start! Buy this. You will save a lot of time! Thanks! ### 5/5 — Excellent tool for Realtors *2025-10-24, version 3.0* Easiest way to calculate mortgage payments. It’s my favorite tool ### 5/5 — 12c review *2025-10-22, version 3.0* I love the app. Thank you for the updates! ### 5/5 — Best…been using since Palm Pilot *2025-10-12, version 3.0* This is the best RPN Financial Calculator available. I’ve been using it since it was available on the Palm pilot. As a licensed CFP, a financial service professional, this app on my phone was critical to my success. ### 5/5 — Spot on replication of the HP12C caluculator *2025-10-08, version 3.0* This app works just like my two HP12C calculators. I’ve retired both now; the app replaces them flawlessly. ### 5/5 — President *2025-10-08, version 3.0* This 12Calc application is so convenient to use and is fully complete. It is my go-to calculator for everything! Many in-depth instructions are included. I use it very often and exclusively, and I find it incredibly convenient. ### 5/5 — Get it! *2025-09-26, version 3.0* It’s been working great for me for many years!! Worth the time and investment. ### 5/5 — Very good HP-12c Emulation *2025-09-24, version 3.0* Better than the original HP calculator, by far. It is much faster. I like the ability to save the tape. If you are not familiar with RPN, but you use a calculator app on your phone, you owe it to yourself to take the 5 minutes it takes to learn how to use it. Much easier on your brain and much less likely to make mistakes, once you get used to it. This emulation is easy to read, particularly if you prefer a different color scheme. I would give it 10 stars if it had an option to turn it into a scientific calculator. ### 5/5 — Much like the HP finance calculator it emulates. *2025-09-20, version 3.0* This calculator has the familiar finance functions that have been standard in most finance calculators released after the famous HP 12C hit the market over 40 years ago. It also has a few more functions than the HP original. Works in both portrait and landscape modes. It’s a nice emulator, better than others I’ve seen. ### 5/5 — HP would approve *2025-09-19, version 3.0* This app emulates the HP-12C as well as any app I’ve used. It’s what I wanted and it’s what I get. Thank you for your continued assurance that it is accurate. I depend on it. ### 5/5 — Absolutely the Best Financial Calculator––and Best Developer *2025-09-17, version 3.0* This calculator remains the absolute best Financial Calculator in the market. In an earlier review I gave this phenomenal app 5 stars but wanted to give it 100. Now, I want to give it 1,000. Without any doubt, this is the #1 calculator of its kind on the market in this CPA's opinion. I use this every day for a wide variety of professional and personal reasons. In addition to doing all the HP 12-C calculations, it has templates for leases, loans, time value of money, multi-year financial ratios, foreign exchange calculations, etc. I use the conversions feature to help me with calculations necessary when I fly general aviation aircraft. One of the best, most useful features is an electronic "tape," which, amazingly, can be e-mailed as a PDF file for printing if need be. This makes the app substantially more valuable than any physical calculator or any comparable app. When I bought this app for my iPhone, I expected to have to pay again for my iPad, but, no, I could download it onto my iPad for no additional cost. This calculator is outstanding. The developer, Ernie Brock, is a genius. He keeps making his app better and better all while staying ahead of Apple’s iOS changes that impact the functionality of the program. I recommend this fantastic app VERY STRONGLY. It continues to get me through CPA seasons, and it makes calculations of pilotage and dead reckoning much easier when I plan cross country flights. ### 5/5 — Hp 12Calc. Love it, great computer *2025-09-15, version 3.0* Been using the 12Calc for years. Have five of them at different locations. I appreciate your help very much. D Bohne ### 5/5 — Simply the Best *2025-09-15, version 3.0* Great App! ### 5/5 — The best *2025-09-13, version 3.0* There are lots of HP12C emulators. This one is the best. Period. ## Most critical reviews (10 lowest-rated) ### 1/5 — Stop it please *2025-09-04, version 3.0* Every time I open this app I get badgered with a review request ### 1/5 — Untrue, this does not have free upgrades *2025-01-21, version 2.8* In fact this a new full charge version of an earlier version. The author was PO’d at needing to rework his UI code because he was making event assumptions that led to the calculator freezing. Lots of annoying quirky gotchas which will endlessly annoy anyone who has spent serious time with an HP 12C. Most annoying to me is that CLX does not clear the X register but instead clears the last digit requiring several presses to clear the register. I don’t know if this is an error or a quirky preference but I do know that it should be optional. ### 1/5 — Amortization *2025-01-05, version 2.8* The previous version I had used calculated everything about a mortgage payment. If I left something blank and hit that button, then it would calculate whatever the information I requested. I.e. interest rate, Payment, years, etc. Now it does not calculate that for me anymore. The previous version worked exactly like my 12 C calculator. Can this be fixed or is there a new way of doing these types of calculations? ### 2/5 — Lost Data *2025-08-30, version 2.9* The past week, every time I open the 12C all the storage registers are zeroed. This renders the app useless to me. Is there a fix? Previously I had no problems. ### 2/5 — IRR and NPV Function Bugs *2019-12-11, version 2.4* I can do almost all the simple time value of money calculations with this calculator. When it comes time to storing values or retrieving values that are necessary for Internal Rate of Return or Net Present Value where I have to store values, the calculator fails and gives me impossible results. I believe this is a big; otherwise the documentation is not specified well enough. ### 3/5 — Fantastic calculator, problematic update *2024-03-13, version 2.8* First of all, nothing beats 12Calc. There is no substitute unless you are using a real 12C, but then 12Calc has all the speed of your iPhone. The latest version, however, is problematic as the font is now white instead of black. Depending on your situation it can be very hard to see. I wish I did not upgrade so I could have kept the previous color scheme of black numbers on a lighter background. Update: Years later this app has been maintained and still works wonderfully. Thank you! ### 3/5 — features whether you want them or not *2023-09-10, version 2.7* Miss being able to lock into landscape mode without having to go to phone settings to allow rotation. Have three HP12 C apps. Don’t find myself using this one as much. ### 3/5 — Fantastic calculator, problematic update *2022-04-27, version 2.7* First of all, nothing beats 12Calc. There is no substitute unless you are using a real 12C, but then 12Calc has all the speed of your iPhone. The latest version, however, is problematic as the font is now white instead of black. Depending on your situation it can be very hard to see. I wish I did not upgrade so I could have kept the previous color scheme of black numbers on a lighter background. **Developer response:** Apple added dark mode last year. Go to the Settings app, select Display & Brightness and then select Light from the APPEARANCE panel. Ding Apple the 2 stars, not the developer! ### 4/5 — Proven Gold Standard *2025-09-29, version 3.0* I still have the original HP 12 C. It is somewhere in my desk since this application came out for the phone and iPad. I have not used the original. this application has been reliable, accurate, and easy to use. It is my go to calculator. ### 4/5 — 12c *2025-08-19, version 2.9* Good ## Most praised reviews (10 highest-rated) ### 5/5 — GP *2026-08-02, version 3.0* Great app ### 5/5 — A Former Finance Professor Says Go For It *2026-07-25, version 3.0* I’ve been using this calculator since it first came out. It’s the best replica I’ve found of the HP-12, the calculator used by finance professionals ### 5/5 — Best *2026-04-28, version 3.0* Best of the best sir. ### 5/5 — Melhor Calculadora *2026-04-04, version 3.0* Excelente, melhor ate mesmo que a HP12C fisica. ### 5/5 — Handy to have on my phone *2026-03-23, version 3.0* I have used an HP 12 C for nearly 35 years. Having it on my phone makes it very convenient. I find the software to work as well as my HP 12 C. ### 5/5 — Better than the Real HP12C! *2026-02-19, version 3.0* Trust me. This app is spectacular! I've used Hewlett Packard calculations since my early years in real estate in late 1970's. I didn't think it could be improved but I was wrong as this emulates all the good features of the physical HP12C and then adds benefits. It is so great to be able to look at the financial registers and see what values are in N, I, PV, PMT, and FV. One of my favorite features is using Clx to eliminate the last number in the X register. The physical HP12C eliminates the whole number so you have to start over. Being able to look at the tape is HUGE if you're wanting to see or verify that you have included all the variables in a long calculation. My fellow REALTORS® don't buy the Hewlett Packard iOS version. I used to train agents at board offices in Tennessee and Alabama on the use of the HP12-C and I've written articles for our nation trade publication, Real Estate Today. I've used the iOS version From Hewlett Packard and this version from Mr. Brock. This version wins HANDS DOWN. I would pay twice or even three times the asking price on 11/8/19. It's unfortunate that Ernest Brock has to battle against Apple's tweaks to it's operating systems which in turn causes tweaks in the App. This is THE go to app for financial calculations in the residential and commercial fields in real estate. To Mr. Brock: I am saving this review so that I can repost it due to an Apple reset. ### 5/5 — Like my HP12C, but better! *2026-02-14, version 3.0* This app is the only calculator I use. ### 5/5 — Get it *2026-01-31, version 3.0* I used a free hp12c app for years. Don't make the same mistake. ### 5/5 — Brilliant *2026-01-23, version 3.0* Have used an HP12C for more than 30 years. An extraordinary classic then by HP. Have the original in my drawer still. Amazing to have this brilliantly executed virtual copy on my iPhone. Very impressed and grateful for the continued updates and expansions of this marvellous App’s capabilities. ### 5/5 — The best! *2026-01-15, version 3.0* I own 4 12c’s and have used them since way back when they first came out. They now all sit in my desk drawer since I bought this app. It does everything a 12c does and more, plus it does it much faster. Thank you Ernie! --- *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 2026-09-03.*