# RPN 30 — An awesome RPN calculator! > Reverse Polish Notation (RPN) calculator with an intuitive interface. (iPhone/iPad app by Ashok Khanna.) - Source: https://appshunter.io/ios/app/rpn-30/id1451413517 (this page in markdown: same URL + `.md`) - Developer: [Ashok Khanna](https://appshunter.io/developer/1451413516) - Category: Utilities, Finance - Price: Free - Rating: 4.70/5 from 154 App Store ratings · 31 written reviews indexed - Age rating: 4+ - Requires: iOS 13.0 · 1 MB - Languages: American English - Released: 2019-02-04 - Data updated: 2026-06-10 - Monetization: free - User reviews in markdown: https://appshunter.io/ios/app/rpn-30/id1451413517/reviews.md ## What is RPN 30? Reverse Polish Notation ("RPN") is an alternative way to complete calculations. Many find it to be more intuitive and user-friendly than the "normal" way of using a calculator. RPN works entering numbers first and then the operator (i.e. 53 47 + will give you 53 + 47 = 100). This is my artistic interpretation of the ideal form for a calculator, taking inspiration from the standard Apple iPhone calculator. Make sure to spend a few minutes to get the hang of the calculator and also read the short help guide (accessed by a long press on the help button) to get the most out of it. No ads, no paid features, always free to use. Please enjoy and leave a review if you like the calculator. ## Key features - Reverse Polish Notation (RPN) calculation - Intuitive user interface - Inspired by standard calculator design - Includes a help guide - Ad-free experience ## Recent user reviews (10 of 31) All indexed reviews: https://appshunter.io/ios/app/rpn-30/id1451413517/reviews.md ### 4/5 — The Store/Recall functionality is awkward. The need to hold two buttons at once is clumsy. *2024-10-03* A generally smooth and uncomplicated system is not applied to the store/ recall implementation ### 5/5 — Love the streamlined operation *2024-09-07* Big buttons and smooth navigation across the pages. You should apply your talents to make a better (similar) Watch experience. All too crowded and clunky. ### 4/5 — Need improvements *2024-08-25* I’ve been using a physical 42S and emulator on my phone for years. The down side is that the keys and display font are small. Apple default calculator app, on the other hand, have very large font and large key size, but it’s not RPN. This calculator here has the potential to be a great alternative to both, but it’s not (yet). 1. Stack display is a bit confusing. Took me a while to figure out Y is on top left corner, and then the next 3 levels up on the right. It would be more consistent if you skip the top left corner position, and just have the stack on the right. 2. While alternate functions are activated by long pressing the number keys/layer, in the advanced function keys/layer, it requires pressing ALT then another key. Why the different behavior? 3. Store/recall does not work at all. ### 3/5 — Huh??? *2024-08-22* I agree with Talasoft guy. I went through engineering school using an HP 15 C calculator. I found this calculator too confusing to use. The developer might want to consider that people looking for an RPN calculator app are those of us who are familiar with RPN and don’t want to carry around a calculator anymore. In other words don’t alienate the people who are most likely to use your app. Furthermore, I am not sure anyone trying to learn RPN will make any sense to what’s happening on this calculator. ### 4/5 — Awesome *2024-08-16* Nice and simple RPN calculator. If the font size of the stack numbers were bigger, it would be perfect. ### 5/5 — Really good *2024-03-17* This is a really good RPN calculator, I couldn’t ask for anything more. **Developer response:** Thanks! ### 5/5 — Perfect *2024-01-21* Couldn’t ask for a better RPN calculator for iOS **Developer response:** Thanks! ### 5/5 — Great app for RPN *2023-12-14* The rpn app I had been using for years is no longer available, so I switched to this one. I’m glad I did; it’s very good. I had a question about using it and emailed the developer; he got right back to me with the information I needed. If you use reverse Polish notation, give this a try. **Developer response:** Thank you very much :-) ### 5/5 — Best calculator on the App Store *2023-11-14* Does what it needs, doesn't beg you for money, stays out of your way and lets you calculate. Thank you so much! **Developer response:** You are welcome :) Thank you for the kind words and using the app. ### 5/5 — Brilliant *2023-08-27* RPN30 is a fantastic implementation of RPN in an easy to understand and use calculator. The HP calculator emulators are good but can be too complex and have unneeded features for 90% of people's need. This will be my go-to everyday calculator. ## Frequently asked questions about RPN 30 ### What is Reverse Polish Notation (RPN)? Reverse Polish Notation (RPN) is a method of calculation where numbers are entered first, followed by the operator. For example, to add 53 and 47, you would enter '53 47 +' instead of '53 + 47'. Many users find this method more intuitive and efficient than standard algebraic notation. ### What are the key features of this RPN calculator? This application provides a calculator that uses Reverse Polish Notation for all calculations. It boasts an intuitive user interface inspired by standard calculator designs and includes a helpful guide accessible via a long press on the help button to assist users in getting the most out of its functionality. ### Is this app free to use? Yes, this application is completely free to use. It does not feature any ads or paid features, ensuring an uninterrupted and cost-free experience for all users. You can enjoy all its functionalities without any financial commitment. ### Who would benefit from using this RPN calculator? This calculator is ideal for individuals who are already familiar with and prefer using Reverse Polish Notation for their mathematical tasks. It's also a great tool for students or professionals looking to explore and adopt a more intuitive calculation method. ### How do I learn to use the RPN calculator? The application includes a short help guide to assist users in understanding and utilizing the RPN functionality. You can access this guide by performing a long press on the help button within the app. Spending a few minutes with the guide will help you get the most out of the calculator. ## Version history (last 5 releases) ### 2.40 — 2022-10-24 Added functions for converting from polar coordinates (in degrees) to rectangular and vice versa. ### 2.35 — 2022-05-31 Some new formulae for engineers ### 2.30 — 2021-04-18 Minor bug fix for Dark Mode ### 2.25 — 2020-07-28 30 Scientific and Financial Functions. New & Improved UI. iPad support and much more! ### 2.0 — 2020-05-31 30 Scientific and Financial Functions. 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User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*