Regina: Software for low-dimensional topology

Latest version: 6.0.1 (February 2021)
Updated packages: 20 May 2021

ContentsPython / C++
What does Regina do?
What's new in version 6.0.1?
Announcement mailing list
License and citation
Moving from Regina 4.x to 5.x
Moving from Regina 5.x to 6.x
Other pages
Supporting data
Building from source
GitHub repository
Past important bugs
Troubleshooting and FAQ


20 May 2021: Added packages for Fedora 34. Follow the install links for details.

14 April 2021: Added packages for Arch Linux! Also, Fedora and openSUSE users can (and should) now install Regina through package repositories instead of downlowding RPMs manually. Follow the install links for details.

12 February 2021: Regina 6.0.1 fixes an issue for Python users in the graphical user interface: you can go ahead and download it now.

10 January 2021: Regina 6.0 is out! This puts some final polish on last month's prerelease (v5.96), with a couple of new features also. If you are upgrading from the much older Regina 5.1, then this is a major overhaul that includes native knot/link support, Python 3, and many other new features and improvements. You can read more about what's new, or go ahead and download it!

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What is Regina?

Regina is a software package for 3-manifold and 4-manifold topologists, with a focus on triangulations, knots and links, normal surfaces, and angle structures.

For 3-manifolds, it includes high-level tasks such as 3-sphere recognition, connected sum decomposition and Hakenness testing, comes with a rich database of census manifolds, and incorporates the SnapPea kernel for working with hyperbolic manifolds. For 4-manifolds, it offers a range of combinatorial and algebraic tools, plus support for normal hypersurfaces. For knots and links, Regina can perform combinatorial manipulation, compute knot polynomials, and work with several import/export formats.

Regina comes with a full graphical user interface, as well as Python bindings and a low-level C++ programming interface.

See the users' handbook for a detailed list of features.

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Click on each thumbnail below for a full-sized version of the screenshot.

Screenshot thumbnail Screenshot thumbnail
Studying 3-manifold
Normal surfaces and
angle structures
Screenshot thumbnail Screenshot thumbnail
Knots and
In-built Python

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The following downloads are available:

Source code

All direct downloads come with SHA-1 checksums and SHA-256 checksums, signed with Ben Burton's GPG key.

If you encounter any problems when you run Regina, you can check the troubleshooting page to see if your problem is discussed there. You also most welcome to contact us for help.


Regina comes with a universal app that runs natively on both Intel and Apple Silicon machines.

On macOS you have several options. Here on the website there is a Python 2 build that uses the system /usr/bin/python, and a Python 3 build that comes bundled with its own copy of Python. There is also a Python 3 version on the App Store (free of course).

Not sure which version to get? Start with the App Store version (but read below).

macOS Version Python 2.7
(System Python)
Python 3.8
(Bundled with app)
Big Sur (11.0)
Catalina (10.15)
Mojave (10.14)
High Sierra (10.13)
Download here Download here
— or —
Download on the Mac App Store

There are some minor differences between the website and App Store versions. The App Store version:

Sandboxing is a security measure that comes with all App Store downloads: it ensures that apps only access files that you explicitly choose through the graphical file dialogs (Open, Save, etc.). For Regina, this means that when you open a Python console or run command-line tools (regina-python, regfiledump, etc.), the only personal files you can access are those in your Downloads folder. You can still access world-readable files, such as those in your Applications folder.


Regina on Windows uses a standard point-and-click installer.

Regina now offers separate 64-bit and 32-bit versions. Almost all modern machines are 64-bit, and this is probably the version you want. If you are not sure:

Windows Version 64-bit installer 32-bit installer
Windows 10
Windows 8.1
Download Download

When running the installer you may see a security warning, such as “Microsoft Defender SmartScreen prevented an unrecognized app from starting ...”, or a message from SmartScreen Filter that “This program might harm your computer”. This is because Microsoft has not added Regina to its database of known applications. Click More info or More options and you should be able to run the installer anyway.


You can download ready-made packages for several GNU/Linux distributions through Regina's online package repositorites. These repositories integrate with your native package manager (apt, dnf/yum, zypper, etc.) to help you keep Regina up-to-date automatically.

For instructions on setting up Regina's package repositories, click on the Install link for your system in the table below.

Regina's GNU/Linux packages are named regina-normal (to avoid conflicting with the other Regina).

Distribution Version Instructions
Arch Linux Rolling release Install
Debian 11.x (bullseye) Install
10.x (buster)
unstable (sid)
Fedora 34 Install
openSUSE Leap 15.2 Install
Ubuntu 21.04 (hirsute) Install
20.10 (groovy)
20.04 LTS (focal)
18.04 LTS (bionic)

Most packages are built only for 64-bit Intel machines (i.e., amd64/x86_64 architectures). This covers almost any typical desktop or laptop nowadays except for Apple Silicon. In addition, the Debian repositories and the Ubuntu 18.04 LTS repositorites also include packages for the 32-bit i386 architecture, and Debian unstable packages are available for every architecture in Debian.

For older versions of GNU/Linux:

For newer versions of GNU/Linux:

For other GNU/Linux distributions:


The iPad app has not yet been updated for Regina 6.0.1. The aim is to update this around April 2021.

Watch this space!


Matthias Goerner has kindly prepared a PyPI package that allows Regina to be used with SageMath. This includes the Python interface to Regina's mathematical engine, but does not include Regina's graphical user interface or command-line tools.

SageMath VersionInstructions
Any Install

Of course, whilst the packages are written to work with any modern version of SageMath, your experiences might vary (particular with an older SageMath and/or operating system). Follow the instructions link above for details.

Source code

For other systems not listed above, you will need to build Regina from its source code.

You can download the source code here.

Please see the separate page on building Regina for instructions on how to build Regina and what libraries and tools you will need to have installed.

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Regina comes with rich documentation for both users and developers.

Users' Handbook

The Regina Handbook is full of screenshots, and walks you through the different things that Regina can do.

You can read the handbook from within Regina by selecting Help → Regina Handbook from the menu. You can also read it here online.

Python/C++ API Documentation

If you are doing Python scripting or C++ programming with Regina, there is extensive API documentation for Regina's mathematical engine. This describes the various objects, classes and functions that Regina makes available to you.

You can read the API documentation by selecting Help → Python API Reference from the menu. You can also read it here online.

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What's new in version 6.0.1?

This is a service release for version 6.0: it fixes an issue for Python users where the Triangulation3 constructor could become unusable in the graphical user interface. This issue did not affect command-line users (e.g., regina-python or SageMath users).

If you missed Regina 6.0 (January 2021) and 5.96 (December 2020), these were a major overhaul from the much older version 5.1:

For Python and C++ programmers:

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Announcement Mailing List

You are welcome to subscribe to the announcement list (this list is still hosted on SourceForge, and will transition at a later date). This is a moderated list with extremely low traffic, and is only used for major announcements such as new releases of Regina. You can subscribe or unsubscribe here.

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License and Citation

The primary developers of Regina are Benjamin Burton, Ryan Budney, and William Pettersson.

Many others have been of assistance with this project, be it through time, knowledge, testing or code. Please see the full list of acknowledgements in the users' handbook.


If you find Regina useful in your research, please consider citing it as you would any other paper that you use. A suggested form of reference is:
Benjamin A. Burton, Ryan Budney, William Pettersson, et al.,
Regina: Software for low-dimensional topology,, 1999–2021.
Or, in BibTeX:
    author = {Benjamin A. Burton and Ryan Budney and William Pettersson and others},
    title = {Regina: Software for low-dimensional topology},
    howpublished = {{\tt http://\allowbreak regina-normal.\allowbreak github.\allowbreak io/}},
    year = {1999--2021}}

Copying & modification

Regina is copyright © 1999–2021, The Regina development team.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Some of this code comes with additional permissions, which allow it to be distributed through online repositories such as Apple's App Store or Google Play. See the full license in the users' handbook for details.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

Detailed License

Regina includes portions of external software for specialised tasks (such as code from SnapPea and SnapPy for some geometric calculations, and code from Normaliz for computing Hilbert bases).

For complete license details, including the full GNU General Public License and information on external software that Regina uses, see the full license in the users' handbook.

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If you have any suggestions, problems, bugs, wishes, frustrations or otherwise miscellaneous comments, we would really love to hear them. This program is permanently under development and we would like to know what people want out of it.

If you have written your own extensions that you think could be worth putting in the main release, please do write and let us know.

Even if you have no comments to make, it's always nice to hear from people using Regina, even if it's just to say hi. We're always interested to hear how this software is being used.

You can contact us by email: our websites are linked to our names in the author list above.

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Privacy Policy

Regina does not collect any data.

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