Free42

v3.0.16 Powerful calculator utility for Windows

Fernando Ortega

A simple, easy-to-use program that quickly performs calculations and offers detailed information on your results.

Perform calculations using a utility styled after the HP-42S calculator that offers multiple functions - Screenshot of Free42
Includes a binary and decimal calculator - Screenshot of Free42
A free program for Windows, by thomas-okken - Screenshot of Free42
User interface - Screenshot of Free42

Binary and decimal scientific calculators based on the HP-42S with all of the familiar functions, plotting and graphical elements.

Free42 is a free and open source HP-42s simulator app and calculator developed by Thomas Okken for Windows. It's light on system resources, user friendly and powerful.

The download has been tested by an editor here on a PC and a list of features has been compiled; see below. We've also created some screenshots of Free42 to illustrate the user interface and show the overall usage and features of this HP-42s simulation program.

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Scientific programmable calculator with enhancements

Free42 is a re-implementation of the HP-42S Scientific Programmable Calculator and HP-82240 Printer.

Free42 not only calculates normal mathematical equations, but can also handle numerical integration or matrices. The graphical display also allows a graphical representation of the results.

It is a complete rewrite, not using any HP code. It does not require an HP-42S ROM image.

Even though it contains significant enhancements compared to the original calculator, Free42 remains fully compatible with the HP-42S, both in its user interface and in its ability to run programs written for the HP-42S.

Free42 is an Open Source project.

Features of Free42

  • Complex Numbers: Perform calculations on complex numbers.
  • Constants: Built-in physical and mathematical constants.
  • Database: Store and recall values.
  • Date and Time Arithmetic: Calculate time intervals.
  • Differential Equations: Solve first- and second-order equations.
  • Exact Computing: Compute with fractions.
  • Financial: Compute NPV, IRR and more.
  • Graphics: Plot functions and data.
  • Matrix: Perform calculations on matrices.
  • Numerical Integration: Calculate integrals.
  • Prime Factorization: Factorize values.
  • Programmable: Define functions and keystrokes.
  • RPN: Reverse Polish Notation.
  • Statistics: Linear regression, chi-square and more.
  • Units Conversion: Convert between units.

Compatibility and License

Is Free42 free?

Free42 is available for free and released under the open source GPLv2 license on Windows from calculators. The license provides the options to freely download, install, run and share this program without any restrictions. The source code for Free42 should be freely available and modifications are certainly permitted as well as the option to inspect the software.

Thomas Okken accepts donations for the continued development of this free software.

What version of Windows can Free42 run on?

Free42 can be used on a computer running Windows 11 or Windows 10. Previous versions of the OS shouldn't be a problem with Windows 8 and Windows 7 having been tested. It comes in both 32-bit and 64-bit downloads.

Other operating systems: The latest Free42 version from 2024 is also available for Mac.

Filed under:
  1. Free42 Download
  2. Free Calculators
  3. Open source and GPL software
  4. HP-42s Simulation Software
Free42 has been picked by our editors as good software.
Free42 has been tested for viruses and malware.
We have tested Free42 v3.0.16 against malware with several different programs. We certify that this program is clean of viruses, malware and trojans.