Free 15C RPN Scientific Calculator

This is a simulator for the HP-15C advanced scientific programmable calculator.

Online version

Click on the calculator image to open the calculator window.


The calculator is also avalable as a downloadable application for various platforms. The downloadable version is (usually) faster than the web version and supports clipboard copy and paste.


(the app is called "Retro 15C" on the App Store because Apple doesn't allow the word "Free" in the app name)


  • Windows EXE Installer (and uninstaller) (5 MB)
  • Windows zip file of executables only (no installer) (6 MB)
  • Mac OS X

  • Mac OS X disk image (10 MB)
  • Mac OS X dashboard widget (0.5 MB)
  • Java

  • Java Swing desktop app (JAR) (1 MB)
  • Other

    For other platforms, you can download the source code and build it yourself. The Qt version is portable to any platform which supports Qt.


    This calculator application should be considered experimental and its results should not be used for anything important. In particular, there are situations where the numeric display is known to be totally wrong.

    This web site and software is not associated with HP or is subsidiaries. HP and the HP logo are trademarks of HP.