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Free42

Free42

HP-42S Calculator Simulator

278 ratings
116 reviews
๐Ÿ”ง Utilities
Free

Details

  • Released
  • Updated
  • November 5, 2009
  • May 5, 2026

Developer

Thomas Okken
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Free42 screenshot #1 for iPhone
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Free42 screenshot #3 for iPhone
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About

This application is a faithful re-implementation of the HP-42S scientific calculator and its associated printer. It offers full functionality without requiring original HP ROM images and is an open-source project.

โœ“HP-42S calculator simulation
โœ“HP-82240 printer simulation
โœ“Open source project
โœ“No HP ROM required
โœ“Complete rewrite
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What users say

Summarized from real user reviews of Free42. Based on 278 reviews and a 4.8/5 average, it highlights the 7 positives and 3 negatives reviewers mention most about this Utilities app.

Positive things

  • ๐Ÿš€Faithful reproduction of HP42S
  • ๐Ÿ‘Identical to physical calculator
  • ๐Ÿ‘Runs all original programs
  • ๐Ÿ‘Convenient to have on phone
  • ๐Ÿ‘Haptic feedback on button presses
  • ๐Ÿ‘Customizable skins
  • ๐Ÿ‘Actively maintained and updated

Negative things

  • ๐Ÿ›Screen not filling entire display on newer devices
  • ๐Ÿ”‡Configurable key click sound missing
  • ๐Ÿ”‡Lack of loud click sound feedback
See all reviews

What's New in Free42

3.3.12

May 5, 2026

Fixed RLN and RRN for negative numbers in BSIGNED mode. More accurate GAMMA for integer arguments.

More

User reviews

Most RecentHighest RatedLowest Rated

THE best calculator app

The HP42s is one of the best calculators ever made. I love Free42. Plus42 is even better, which I was happy to buy to support the development of both apps.
IT Problem SolverIT Problem Solver

One request

Big fan from forever ago. Had free42 on all my PalmOS devices, Android, PC, and i0S since my IPhone 1. However, the current version on iOS has the oldest built-in skins instead of the newest ones. Please fix?
DaveboydDaveboyd

Works great

Wish there was a 41 CV version to replace my real one. But this is a good replacement.
StikypeteStikypete

Would recommend

This is an awesome RPN calculator, and does all the things you need and more.
QoolQuyQoolQuy

Best free app for thinking people

This app is a service to mankind. Especially if you only speak RPN.
Soutie in AusSoutie in Aus
See 111 more reviews

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User experience

๐Ÿž

Reported Bugs

2 issues

Occasional issues with Solver function

Bug

Store and Recall functions not working properly

Bug
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Requested Features

3 requests

Display all registers (X, Y, Z, T, Last X) simultaneously

Feature

Ability to share/transfer programs between devices

Feature

Improved use of screen real estate on larger displays

Feature

FAQ

What does Free42 do?

Free42 is a re-implementation of the HP-42S scientific calculator and the HP-82240 printer. It provides the full functionality of these classic devices in a software application.

Do I need an HP ROM image to use Free42?

No, Free42 is a complete rewrite and does not require any HP-42S ROM images to function. You can use it immediately after installation.

Is Free42 free to use?

Yes, Free42 is an open-source project released under the GNU General Public License, version 2. It is completely free to download and use.

What platforms is Free42 available on?

The provided data does not specify the exact platforms Free42 is available on, but as a simulator, it is likely designed for desktop operating systems or mobile devices.

What are the main features of Free42?

The primary features include a faithful simulation of the HP-42S scientific calculator and the HP-82240 printer. It is also an open-source project, meaning its source code is publicly available and can be modified.