Slicer relies on a number of large third-party libraries (such VTK, ITK, DCMTK), which take a long time to build and use a lot of disk space. Currently, build requires disk space of 15GB (for release mode) or 60GB (for debug mode). Build time on a desktop computer is typically 3-4 hours, on a laptop it may take 8-12 hours.

Install prerequisites

  • CMake version >= 3.16.3.

    • Avoid versions with known Slicer build issues:

  • Git >= 1.7.10

    • Note: CMake must be able to find git.exe and patch.exe. If git is installed in the default location then they may be found there, but if they are not found then either add the folder that contains them to PATH environment variable; or set GIT_EXECUTABLE and Patch_EXECUTABLE as environment variables or as CMake variables at configure time.

  • Visual Studio: any edition can be used (including the free Community edition), when configuring the installer:

    • Enable Desktop development with C++ and in installation details

    • Enable the MSVC v143 - VS2022 C++ x64... (Visual Studio 2022 v143 toolset with 64-bit support) component - in some distributions, this option is not enabled by default.

    • Enable the latest Windows10 SDK component - without this CMake might not find a compiler during configuration step.

  • Qt5: Download Qt universal installer and install Qt 5.15.2. In the Select Components tab of the universal installer, Qt version and its components can be selected by expanding the Qt category. Components required: MSVC2019 64-bit, Qt WebEngine. Installing Sources and Qt Debug Information Files are recommended for debugging (they allow stepping into Qt files with the debugger in debug-mode builds).

    • Note: These are all free, open-source components with LGPL license which allow free usage for any purpose, for any individuals or companies.

  • NSIS (optional): Needed if packaging Slicer. Make sure you install the language packs.


Other Visual Studio IDE and compiler toolset versions

  • Visual Studio 2019 (v142) toolset is not tested anymore but probably still works.

  • Visual Studio 2017 (v141) toolset is not tested anymore but probably still works. Qt-5.15.2 requires v142 redistributables, so either these extra DLL files need to be added to the installation package or each user may need to install “Microsoft Visual C++ Redistributable” package.

  • Cygwin and Mingw: not tested and not recommended. Building with cygwin gcc not supported, but the cygwin shell environment can be used to run utilities such as git.

Set up source and build folders

  • Create source folder. This folder will be referred to as <Slicer_SOURCE> in the following. Recommended path: C:\D\S

    • Due to maximum path length limitations during build the build process, source and build folders must be located in a folder with very short (couple of characters) total path length.

    • While it is not enforced, we strongly recommend you to avoid the use of spaces for both the source directory and the build directory.

  • Create build folder. This folder will be referred to as <Slicer_BUILD> in the following. Recommended path: C:\D\SR for release-mode build, C:\D\SD for debug-mode build.

    • You cannot use the same build tree for both release or debug mode builds. If both build types are needed, then the same source directory can be used, but a separate build directory must be created and configured for each build type.

    • How to decide between Debug and Release mode?

      • Release mode build: runs at same speed as official build, requires less disk space (about 15GB); but step-by-step debugging is not available

      • Debug mode build: allows debugging (adding breakpoints, step through the code line by line during execution, watch variables); but it may run 5x or more slower, requires more space (about 60GB), and user interface editing in Qt designer is not available

  • Download source code into Slicer source folder from GitHub:

    • The following command can be executed in Slicer source folder to achieve this: git clone . (note the dot at the end of the command; the . is needed because without that git would create a Slicer subfolder in the current directory)

  • Configure the repository for developers (optional): Needed if changes need to be contributed to Slicer repository.

    • Right-click on <Slicer_SOURCE>/Utilities folder in Windows Explorer and select Git bash here

    • Execute this command in the terminal (and answer all questions): ./

    • Note: more information about how to use git in Slicer can be found on this page

Configure and build Slicer

Build takes several hours. Warnings will appear during the build (it is practically not feasible to have warning-free builds in large multi-platform projects that rely on third-party libraries), but there must not be any errors. If any problems occur, read the Common errors section.

Using graphical user interface (alternative solution)

  • Run CMake (cmake-gui) from the Windows Start menu

  • Set Where is the source code to <Slicer_SOURCE> location

  • Set Where to build the binaries to <Slicer_BUILD> location. Do not configure yet!

  • Add Qt5_DIR variable pointing to Qt5 folder: click Add entry button, set Name to Qt5_DIR, set Type to PATH, and set Value to the Qt5 folder, such as C:\Qt\5.15.2\msvc2019_64\lib\cmake\Qt5.

  • Click Configure

  • Select your compiler: Visual Studio 17 2022, and click Finish

  • Click Generate and wait for project generation to finish (may take a few minutes)

  • Click Open Project

  • If building in release mode:

    • Open the top-level Slicer.sln file in the build directory in Visual Studio

    • Set active configuration to Release. Visual Studio will select Debug build configuration by default when you first open the solution in the Visual Studio GUI. If you build Slicer in release mode and accidentally forget to switch the build configuration to Release then the build will fail. Note: you can avoid this manual configuration mode selection by setting CMAKE_CONFIGURATION_TYPES to Release in cmake-gui.

  • Build the ALL_BUILD project

Run Slicer

Run <Slicer_BUILD>/Slicer-build/Slicer.exe application.

Note: Slicer.exe is a “launcher”, which sets environment variables and launches the real executable: <Slicer_BUILD>/Slicer-build\bin\Release\SlicerApp-real.exe (use Debug instead of Release for debug-mode builds).

Test Slicer

  • Start Visual Studio with the launcher:

Slicer.exe --VisualStudioProject
  • Select build configuration. Usually Release or Debug.

  • In the “Solution Explorer”, right click on RUN_TESTS project (in the CMakePredefinedTargets folder) and then select Build.

Package Slicer (create installer package)

  • Start Visual Studio with the launcher:

Slicer.exe --VisualStudioProject
  • Select Release build configuration.

  • In the “Solution Explorer”, right click on PACKAGE project (in the CMakePredefinedTargets folder) and then select Build.

Debug Slicer

  • C++ debugging: Visual Studio is recommended on Windows, see instructions.

  • Python debugging: multiple development environments can be used, see instructions.

Common errors

Custom Slicer and CTK widgets do not show up in Qt designer

Qt Designer can only use designer plugins (in c:\D\SR\Slicer-build\bin\designer and c:\D\SR\CTK-build\CTK-build\bin\designer) that are built in the same mode (e.g. Debug or Release).

In pre-built Qt packages (downloaded from Qt website) Qt Designer is only provided in Release mode. If Qt is built from source in Release mode (default) or Release and Debug mode then Qt designer will be in Release mode. In all these cases, Qt Designer can be used only if Slicer is built in Release mode.

If Qt is built from source in Debug mode mode then Qt designer will be in Debug mode. In this case, Qt Designer can be used only if Slicer is built in Debug mode.

Other problems

See list of issues common to all operating systems on Common errors page.