Plus42 vs HP
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
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.
HP
Emulates classic Hewlett Packard RPN scientific calculators from the 1970s. Experience the original HP-35, HP-45, and HP-21 models on your iPhone.
- RPN calculator emulation
- HP-35 model
- HP-45 model
- HP-21 model
- Classic scientific calculator interface
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The classic Hewlett Packard RPN (Reverse Polish Notation) calculators. - HP-35, HP-45. First pocket scientific calculators (1972). - HP-21. 2nd gen of the HP-35 (1975)
Screenshots
Verdict
The clearest difference is price: HP at Free against Plus42's $9.99. Plus42's advantage is ratings volume (79 vs 5) and chart position (#110 vs unranked). On rating, review sentiment, update cadence and ads 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
HP is free to download; Plus42 costs $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 — 4.9 for Plus42 against 5.0 for HP. That said, the two scores are not equally well evidenced: Plus42 has 79 ratings behind it against 5, so its average is the more settled of the two. Written reviews are what separate them: 92% of Plus42's written reviews are positive against 100% of HP's.
Plus42 ships an update weekly, HP every 11 days. The most recent releases landed on September 22, 2026 and September 21, 2026 respectively.
| Parameter | Plus42 | HP |
|---|---|---|
| Price | $9.99 | Free — better |
| Rating | 4.9 (79 ratings) | 5.0 (5 ratings) — better |
| Positive reviews | 92.3% of reviews | 100.0% of reviews — better |
| Number of ratings | 79 — better | 5 |
| Update frequency | Weekly — better | Every 11 days |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Best chart rank | #110 — better | — |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 12.0 — better | 17.2 |
| Further details — not scored | ||
| Size | 11 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Thomas Okken | Enrique Haro |
Customer experience
Plus42
HP
In-app purchases
Plus42
No in-app purchases
HP
No in-app purchases
