RPNPro vs |RPN| Scientific Calculator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RPNPro
This calculator utilizes Reverse Polish Notation (RPN) for input, mirroring the functionality of classic HP calculators. It features a four-level stack with X, Y, Z, and T registers, displaying the X register in decimal, hexadecimal, and binary.
- Reverse Polish Notation (RPN) input
- Four-level stack (X, Y, Z, T registers)
- Decimal, hexadecimal, and binary display
- Modeled after HP calculators
- Designed for software engineers
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RPNPro is a calculator for software engineers. RPNPro uses RPN (Reverse Polish Notation) as an input scheme. It is based on the same four level stack model as provided by the original HP (Hewlett-Packard) calculators, featuring X, Y, Z and T registers. The contents of the X register are always shown in decimal, hexadecimal and binary notation.
|RPN| Scientific Calculator
This calculator app uses Reverse Polish Notation for powerful calculations. It offers customizable color schemes, layouts, and online help, designed for flexibility and usability. All features are unlocked with a one-time purchase.
- Reverse Polish Notation (RPN)
- Viewable stack
- Selectable portrait/landscape layouts
- Customizable color schemes
- Online visual help
- No ads or in-app purchases
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|RPN| Scientific Calculator is a calculator which features a variety of color schemes and layouts. It utilizes Reverse Polish Notation, a viewable stack, selectable portrait and landscape layouts, online visual help and many more. The application is meant to be as flexible and powerful as possible, without sacrificing usability. |RPN| does not have ads, and never will, nor does it use in-app purchases. All functionality comes with the purchase. Here is a youtube playlist with some helpful videos: https://www.youtube.com/playlist?list=PLucgGVHO2sKhnnNf1gapHS4Zy7u69VGAs
Screenshots
Verdict
The clearest difference is price: RPNPro at Free against |RPN| Scientific Calculator's $0.99. RPNPro also leads on rating (5.0 vs 2.3) and iOS requirement (9.1 vs 16). |RPN| Scientific Calculator's advantage is update cadence (fortnightly vs every 37 months) and review sentiment (60% vs 50%). On ads, in-app purchases and device support 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
RPNPro is free to download; |RPN| Scientific Calculator costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
RPNPro holds the better App Store score, 5.0 against 2.3. Both are backed by a comparable volume of ratings — 1 and 3 respectively. Written reviews complicate that: 50% of RPNPro's written reviews are positive against 60% of |RPN| Scientific Calculator's, so the app with the better star average is not the one people write more warmly about.
RPNPro ships an update every 37 months, |RPN| Scientific Calculator fortnightly. The most recent releases landed on October 14, 2026 and October 24, 2026 respectively.
| Parameter | RPNPro | |RPN| Scientific Calculator |
|---|---|---|
| Price | Free — better | $0.99 |
| Rating | 5.0 (1 ratings) — better | 2.3 (3 ratings) |
| Positive reviews | 50.0% of reviews | 60.0% of reviews — better |
| Number of ratings | 1 | 3 — better |
| Update frequency | Every 37 months | Fortnightly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 9.1 — better | 16 |
| Further details — not scored | ||
| Size | 1 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Felix Meier | Bradley Smith |
Customer experience
RPNPro
|RPN| Scientific Calculator
In-app purchases
RPNPro
No in-app purchases
|RPN| Scientific Calculator
No in-app purchases
