Free42 vs HP
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Free42
This app is a faithful open-source simulation of the HP-42S scientific calculator and its associated printer. It offers a complete rewrite without requiring original ROM images, allowing users to run existing programs on their mobile devices.
- HP-42S calculator simulation
- HP-82240 printer simulation
- Open-source project
- Runs original HP-42S programs
- No ROM image required
- Customizable skins
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Free42 is a re-implementation of the HP-42S calculator and the HP-82240 printer. It is a complete rewrite, not using any HP code, and it does not require an HP-42S ROM image. Free42 is an Open Source project. The executables and source code are released under the terms of the GNU General Public License, version 2. All third-party code used in Free42 is either in the public domain, or licensed under terms compatible with GPLv2, or used with the authors' permission.
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 ratings volume: Free42 at 288 against HP's 66. Free42 also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17.2). On price, rating, review sentiment and update cadence 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
Free42 holds the better App Store score, 4.8 against 4.6. Both are backed by a comparable volume of ratings — 288 and 66 respectively. Written reviews complicate that: 94% of Free42's written reviews are positive against 100% of HP's, so the app with the better star average is not the one people write more warmly about.
Free42 ships an update weekly, HP every 11 days. The most recent releases landed on November 13, 2026 and November 14, 2026 respectively.
| Parameter | Free42 | HP |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (288 ratings) — better | 4.6 (66 ratings) |
| Positive reviews | 94.4% of reviews | 100.0% of reviews — better |
| Number of ratings | 288 — better | 66 |
| Update frequency | Weekly — better | Every 11 days |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 15.0 — better | 17.2 |
| Further details — not scored | ||
| Size | 9 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Thomas Okken | Enrique Haro |
Customer experience
Free42
HP
Bugs and requests
Free42
Reported bugs
2 issues- Occasional issues with Solver function
- Store and Recall functions not working properly
Requested features
3 requests- Display all registers (X, Y, Z, T, Last X) simultaneously
- Ability to share/transfer programs between devices
- Improved use of screen real estate on larger displays
HP
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Free42
No in-app purchases
HP
No in-app purchases
