PYTHIA Documentation

PYTHIA is documented in several ways, both online and in publications. The main reference is the PYTHIA 8.3 publication listed below.

License information

PYTHIA 8 is licensed under the GNU General Public Licence version 2 or later. Please respect the MCnet Guidelines for Event Generator Authors and Users.

The program and the documentation is Copyright © 2024 Torbjörn Sjöstrand.


PYTHIA is the product of many years of work developing models and implementing them in an event generator. When you use PYTHIA for a publication, both the most recent PYTHIA manual (currently A comprehensive guide to the physics and usage of PYTHIA 8.3) and the paper(s) introducing the physics model you are using, must be cited. Note that in some cases the used physics models are not created by, or only partially created by, the PYTHIA authors, underlining the importance of proper citations.


The main publicly accessible repository of validation plots for PYTHIA 8 is the external MCplots web site. This contains extensive browsable validation plots for PYTHIA 8 and comparisons to other generators.

The MCplots validation site is based on the Rivet analysis preservation system and the Test4Theory project on LHC@home. If you find this resource useful, consider joining the LHC@home project as a volunteer and select the Test4Theory project. If you use results from MCplots in your work, for presentations, or in discussions, please also endeavour to cite the MCplots paper.

Note: there is normally a delay after a new PYTHIA release before it can appear on MCplots. Therefore, the PYTHIA versions shown available on MCplots are typically a few versions behind the most recent one.

Software sustainability

PYTHIA strives to adhere to FAIR scientific software principles. Click the badge below to see our self-evaluation, and get in touch if you see a place where we could improve our FAIRness.

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HTML manuals and Doxygen

Here you can find online versions of the PYTHIA manual and a Doxygen representation of the code, dating back to Pythia 8.051, which was the first version to have a such a manual. For earlier versions in the Pythia 8 series, you have to download the code and study the contained manual.

PYTHIA 8.3 series:

PYTHIA 8.2 series:

PYTHIA 8.1 series:

PYTHIA 8.0 series: