RPN Calculator 48 vs Plus42
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RPN Calculator 48
This app offers a scientific calculator with Reverse Polish Notation (RPN) functionality, providing an alternative to the default calculator. It features a large, easy-to-read display, a 100-entry stack, and extensive undo/redo capabilities. Its design is inspired by classic HP calculators.
- Reverse Polish Notation (RPN)
- Scientific calculator functions
- Swipe gestures for undo/redo
- 100 entry stack
- 6 memory buttons
- State saving on exit
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RPN Calculator 48 is a polished RPN replacement for Apple's calculator app: - Same scientific functionality as Apple's calculator app* - Use swipe gestures to undo and redo operations! - Starts quickly - Large buttons - Easy-to-read display - 100 entry stack - 6 memory buttons (A-F) - 50+ levels of undo/redo - Saves state on exit The ergonomics (screen and keyboard layout) of RPN Calculator 48 were inspired by HP's outstanding 48-series calculator. RPN Calculator 48 is made by the developer of tChess (the critically acclaimed iPhone chess game) and Learn Chess (the Apple Staff Favorite e-book). * This app is not an HP 48 emulator.
Plus42
This advanced scientific calculator simulates the classic HP-42S RPN calculator with enhanced features. It offers algebraic expressions, unit conversions, directories for storage, a larger resizable display, financial functions, and 2D plotting with integral and root finding.
- HP-42S RPN calculator simulation
- Algebraic expressions
- Attached units and conversions
- Program and variable directories
- Resizable 8-row, 22-column display
- Time value of money and amortization
- 2D function plotting with zoom and pan
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Plus42 is an advanced scientific programmable calculator, based on Free42. Free42, in turn, is a complete re-implementation of the HP-42S scientific programmable RPN calculator, which was made from 1988 until 1995 by Hewlett-Packard. Free42 is a complete rewrite and contains no HP code whatsoever. Plus42 builds on Free42 and adds: Algebraic expressions modeled after those used on the HP-27S and HP-17B/19B; attached units and unit conversions modeled after those used on the HP-48/49/50 series; directories for more organized storage of programs and variables; a larger display, with 8 rows and 22 columns (131x64 pixels) by default, which the user may resize at will; time value of money and amortization schedules; and two-dimensional plotting of functions, with ability to zoom and pan, and find integrals and roots from points in the plot.
Screenshots
Verdict
The clearest difference is update cadence: Plus42 at weekly against RPN Calculator 48's every 14 months. Plus42 also leads on device support (3 vs 1) and iOS requirement (15.0 vs 18.0). RPN Calculator 48's advantage is price ($3.99 vs $9.99) and chart position (#196 vs unranked). On rating, review sentiment, ads and in-app purchases 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 Calculator 48 costs $3.99 and Plus42 $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.8 for RPN Calculator 48 against 4.9 for Plus42. Both are backed by a comparable volume of ratings — 246 and 79 respectively. Written reviews are what separate them: 96% of RPN Calculator 48's written reviews are positive against 92% of Plus42's.
RPN Calculator 48 ships an update every 14 months, Plus42 weekly. The most recent releases landed on October 29, 2026 and October 27, 2026 respectively.
| Parameter | RPN Calculator 48 | Plus42 |
|---|---|---|
| Price | $3.99 — better | $9.99 |
| Rating | 4.8 (246 ratings) | 4.9 (79 ratings) — better |
| Positive reviews | 95.9% of reviews — better | 92.3% of reviews |
| Number of ratings | 246 — better | 79 |
| Update frequency | Every 14 months | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Free — better |
| Best chart rank | #196 — better | — |
| Devices | iPhone | iPhone, iPad, iPod — better |
| Requires iOS | 18.0 | 15.0 — better |
| Further details — not scored | ||
| Size | 1 MB | 11 MB |
| Age rating | 4+ | 4+ |
| Developer | Tom Kerrigan | Thomas Okken |
Customer experience
RPN Calculator 48
Plus42
Bugs and requests
RPN Calculator 48
Reported bugs
1 issue- Display issues in landscape mode on iPad
Requested features
3 requests- Add haptic feedback for key presses
- Implement ability to recall previous calculations from stack
- Improve landscape mode support on iPad
Plus42
Not enough reviews yet to summarise bugs or requests.
In-app purchases
RPN Calculator 48
No in-app purchases
Plus42
No in-app purchases
