RPN Calc vs RPN
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RPN Calc
This app provides a straightforward reverse Polish notation (RPN) calculator experience, inspired by classic HP models. It offers a clean interface with large buttons for quick calculations on iPhone, iPad, and Apple Watch, along with a convenient Today Extension for immediate access.
- Reverse Polish Notation (RPN) input
- Clean, simple interface
- Large, easy-to-press buttons
- iPhone, iPad, and Apple Watch support
- Today Extension for quick access
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A simple reverse polish notation calculator loosely based on my trusty HP-32SII that runs on iPhone, iPad, and Apple Watch! If you are familiar with HP RPN calculators, the operation of this calculator should seem very straightforward - albeit simplified. It can't be programmed, and it doesn't handle binary, or hexadecimal numbers. But, it has a clean, simple interface with large, easy to press buttons. It has all of the functions required for quick calculations when your iPhone is handier than your computer or calculator. And, remember those cool calculator watches from the 1980s? Unfortunately, none of them were RPN. RPN Calc brings a reverse polish notation watch calculator to the Apple Watch! In addition to the standard RPN Calculator app that runs on iPhone, iPad, and Apple Watch, RPN Calc includes a handy micro RPN Calc Today Extension available for convenient access to quick calculations from the pull down Today screen.
RPN
This utility app functions as a reverse Polish notation calculator. Users input numbers and operations using a stack-based interface to perform calculations. It's designed for straightforward mathematical tasks.
- Reverse Polish Notation (RPN) input
- Stack-based operation
- Intuitive digit and operation buttons
- Clear result display
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Simple reverse polish notation calculator. To make an operation you tap the number using the digit buttons. When you want to insert the number into the stack you press the orange button "Enter". When you're done inserting the numbers just tap the operation to do it. The result will be displayed but not put again into stack. Example: 6+7 is 6 enter, 7 enter +
Screenshots
Verdict
The clearest difference is price: RPN at Free against RPN Calc's $0.99. RPN also leads on update cadence (monthly vs every 3 months). RPN Calc's advantage is review sentiment (38% vs 0%) and in-app purchases (none vs 1). On ads, monetization model and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
RPN is free to download; RPN Calc costs $0.99 up front. RPN sells 1 one-off in-app purchase. RPN Calc asks for nothing beyond the download.
RPN Calc ships an update every 3 months, RPN monthly. The most recent releases landed on October 31, 2026 and November 1, 2026 respectively.
| Parameter | RPN Calc | RPN |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 4.0 (6 ratings) — better | — |
| Positive reviews | 37.9% of reviews — better | 0.0% of reviews |
| Number of ratings | 6 — better | — |
| Update frequency | Every 3 months | Monthly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | Free |
| Devices | iPhone, iPad, Apple Watch — better | iPhone |
| Requires iOS | 16.0 — better | 16.6 |
| Further details — not scored | ||
| Size | 3 MB | 5 MB |
| Age rating | +4 | 4+ |
| Developer | James Mattis | Tomas Stankiewicz Baldassarri |
Customer experience
RPN Calc
RPN
In-app purchases
RPN Calc
No in-app purchases
RPN
- Stack LCD$0.49
