What is the THEMEPACK file format?
.themepack is a system file associated with Microsoft Windows 7. .themepack files store desktop themes in .CAB archive format. They can be used to export or import custom Windows 7 (and later) desktop themes. Desktop themes can also be saved as .THEME files, which have some limitations regarding external resources and files. Windows 8 and later introduced the .deskthemepack format, which is not backward compatible with Windows 7; however, Windows 10 and 11 can still apply .themepack files through a legacy code path.
Windows desktop themes
Desktop themes are used for customizing the desktop user interface. Themes allow users to customize sounds, background images, or window color settings. Users can maintain multiple themes and switch between them easily. Themes can define the following interface elements:
- Background image,
- Color and appearance settings,
- System icons,
- Mouse pointer cursors,
- System sounds,
- Screensaver.
All theme settings and additional files are saved inside .themepack files. Double-clicking a .themepack installs it automatically via the Windows shell handler. Archive utilities such as 7-Zip can open the .themepack container directly to inspect or extract its contents.
Security & safety
RISK: MEDIUMTHEMEPACK files are CAB archives and can technically embed executable files (screensavers are .scr = PE executables). A malicious .themepack could include a hostile screensaver. Always download theme packs from reputable sources. The Windows shell handler does not execute files during installation - it only copies assets and writes registry keys - but embedded .scr files activate if selected as screensaver. Inspect contents with 7-Zip before installing theme packs from unknown sources.
Format details
in a nutshellPrograms that open THEMEPACK files
Windows5 apps
Microsoft Windows Personalization Control Panel
Built-in The .themepack handler is part of the Windows shell - double-click installs automatically. 
Microsoft Windows 8
Paid Double-click to apply; note that Windows 8 natively uses .deskthemepack for its own themes. 
Windows Personalization (built-in shell handler)
Built-in Double-click the .themepack file - Windows applies the theme automatically and opens the Personalization pane. Technical details
deep spec| Container | Microsoft Cabinet (CAB) - magic bytes 4D 53 43 46 ("MSCF") |
| Compression | LZX or MSZIP (per-entry CAB compression) |
| Encoding | Binary (CAB container) |
| Byte order | Little-endian |
| Inner configuration file | .theme - plain INI-format text file referencing wallpapers, sounds, cursors, and screensaver |
| Wallpaper formats | JPEG and PNG images, typically in a DesktopBackground subfolder |
| Typical file size | 1 MB - 50 MB (depends on wallpaper count and resolution) |
| Integrity | CAB per-block checksums (optional field in CAB header) |
| Shell integration | Double-click installs theme automatically via Windows shell handler |
| Introduced with | Windows 7 (October 22, 2009) |
| Windows 8+ successor | .deskthemepack - not backward compatible with Windows 7 |
| Backward compatibility | Windows 10 and 11 can still apply .themepack files via legacy code path |
| Additional content | May include cursor files (.cur/.ani), sound clips, and screensaver references |
| Inspection tools | 7-Zip or WinRAR can open and extract contents as a standard CAB archive |
| Released | 2009 (Windows 7) |
| Latest version | Windows 7/8/10 era; superseded by .deskthemepack for Windows 8+ |
| Specification | learn.microsoft.com |
THEMEPACK conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about THEMEPACK files.
