Best Free42 Alternatives ranked by AI · updated Aug 2026

✅ Update queued — the AI is re-ranking this list. The page will refresh shortly.

This page is already up to date.

Free42 is an open-source emulator of the HP-42S scientific programmable calculator for desktop and mobile platforms. It targets engineers, scientists, students, and users who want accurate RPN calculations, programming, and HP-42S compatibility.

Developer: Thomas Okken Price: Free 🎯 thomasokken.com/free42

🔓 Open Source calculator scientific rpn programmable

Top 6 Free42 alternatives

Plus42

Thomas Okken

💡 Pick it when you want Free42 compatibility with more functions and a broader scientific calculator feature set.

Plus42 is a programmable RPN scientific calculator based on the Free42 engine, with additional functions and a larger feature set. It is...

Pros

Adds more functions and capabilities than Free42 while retaining a familiar RPN workflow
Maintains strong compatibility with HP-42S-style programs
Available across major desktop and mobile platforms

Cons

More complex than Free42 for users who only need HP-42S emulation
Still has an older calculator-style interface rather than a modern worksheet UI
Less widely documented by third parties than HP-42S emulators

Free

Alternatives to Plus42 → Visit site

Emu42

Christoph Giesselink

💡 Pick it if you want a dedicated Windows HP-42S emulator instead of Free42's broader multi-platform focus.

Emu42 is a Windows emulator for the HP-42S programmable scientific calculator. It is aimed at users who need close HP-42S behavior, programmable...

Pros

Provides a desktop-focused HP-42S emulation experience
Supports RPN programs and calculator-state workflows
Runs well for users who prefer a resizable Windows application

Cons

Primarily targets Windows rather than mobile and cross-platform users
Interface is more utilitarian than Free42's polished mobile ports
Smaller user community and documentation ecosystem than Free42

Free

Alternatives to Emu42 → Visit site

PCalc

💡 Pick it if you want a polished Apple calculator with RPN mode instead of exact HP-42S emulation.

PCalc is a powerful calculator app for iOS and macOS with a customizable interface and advanced features.

$9.99

Alternatives to PCalc → Visit site

Qalculate!

💡 Pick it if you need symbolic math, units, and typed expressions more than HP-42S program compatibility.

Qalculate! is a versatile calculator with a focus on easy-to-use interface and extensive mathematical functions.

Pros

Extensive mathematical functions
User-friendly interface

Cons

Less advanced than some competitors
Occasional stability issues

Free

Alternatives to Qalculate! →

SpeedCrunch

💡 Pick it if you prefer fast desktop expressions and calculation history over an HP-style RPN interface.

SpeedCrunch is a high-precision scientific calculator that offers a fast and natural way to do mathematical calculations.

Free

Alternatives to SpeedCrunch → Visit site

RPN Calculator

RPNCalc

💡 Pick it for quick, installation-free RPN calculations when HP-42S emulation and programming are unnecessary.

RPN Calculator is a browser-based calculator built around reverse Polish notation and common scientific operations. It suits users who want quick RPN...