RPN Calc vs iSetSquare
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.
iSetSquare
This utility app functions as a digital goniometer, utilizing your device's gyroscope to measure angles and rotations. It offers multiple unit modes, calibration options, and a scrollable ruler for precise measurements.
- Measure relative angles and rotation
- 5 Unit modes
- Background or foreground display rotation
- Gyrometer fine calibration
- Motion sensitive or manual lock mode
- Scrollable ruler (inch or cm)
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Goniometer tool using the gyroscope sensor. Features: - Measure relative angles and rotation counter - 5 Unit modes, with a quick switch - Background or foreground display rotation - Fine calibration of the gyrometer - Motion sensitive or manual lock mode - Scrollable ruler (inch or cm) - Check out all our products on www.plaincode.com
Screenshots
Verdict
The clearest difference is review sentiment: iSetSquare at 86% against RPN Calc's 34%. iSetSquare also leads on iOS requirement (9.0 vs 16.0). RPN Calc's advantage is rating (4.0 vs 3.2) and update cadence (every 3 months vs every 17 months). On ratings volume, 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
RPN Calc costs $0.99 and iSetSquare $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.
RPN Calc holds the better App Store score, 4.0 against 3.2. Both are backed by a comparable volume of ratings — 6 and 6 respectively. Written reviews complicate that: 34% of RPN Calc's written reviews are positive against 86% of iSetSquare's, so the app with the better star average is not the one people write more warmly about.
RPN Calc ships an update every 3 months, iSetSquare every 17 months. Both last shipped on November 6, 2026.
| Parameter | RPN Calc | iSetSquare |
|---|---|---|
| Price | $0.99 — better | $1.99 |
| Rating | 4.0 (6 ratings) — better | 3.2 (6 ratings) |
| Positive reviews | 34.3% of reviews | 86.0% of reviews — better |
| Number of ratings | 6 | 6 |
| Update frequency | Every 3 months — better | Every 17 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free — better | Paid |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, iPod |
| Requires iOS | 16.0 | 9.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 13 MB |
| Age rating | 4+ | 4+ |
| Developer | James Mattis | Peter Breitling |
Customer experience
RPN Calc
iSetSquare
In-app purchases
RPN Calc
No in-app purchases
iSetSquare
No in-app purchases
