This tool is an open-source standalone visual interface to make using the Windows 10 compact.exe function more available to more people, allowing game and program installations to be compressed with minimal or no performance loss.
The compression used by compact.exe is similar to the built-in NTFS compression in that it is transparent. Compressed files and programs can still be accessed as if nothing has changed and show up in Explorer as they normally would — they'll just be decompressed on the fly at runtime. However, the newer algorithms used by Compact are much more efficient.
Download the standalone program from GitHub Releases
Use this tool to:
- Compress program folders (e.g. Adobe Photoshop: 1.71 GB --> 886 MB)
- Compress game install folders (e.g. Portal 2: 11.8 GB --> 7.88 GB)
- Compress any other folder on your computer.
See the Wiki for a list of 
and 
that have been tested
For most modern computers there will be no (or very little) performance loss. Those with older HDDs may even see a decent performance gain in the form of reduced loading times as the smaller files means it takes less time to read programs and games into RAM.
- More accurate reporting than the built-in Windows command-line tool (as there are some bugs with parsing that Microsoft needs to fix)
- Get compression estimates for games based on results from the Wiki submissions
- Analyze the status of existing folders
- Integration into Explorer context menus for easier use.
- Option to shutdown computer on completion
- Integration with the online database for analysis and compression estimates
Windows 10 includes a little-known but very useful tool called Compact that allows one to compress folders and files on disk, decompressing them at runtime. With any modern CPU, this added load is hardly noticed, and the space savings are of most use on those with smaller SSDs.
As program folders and games can be shrunk by up to 60%, this has the added bonus of potentially reducing load times - especially on slower HDDs.
More information on the inbuilt Windows function can be found here
This tool is intentionally designed to only compress folders and files. Whole drives and entire Windows installations cannot be modified from within CompactGUI - users seeking that functionality should use the command-line version built into Windows (this is intentional).
The compression used by compact.exe is similar to the built-in NTFS compression in that it is transparent. Compressed files and programs can still be accessed as if nothing has changed and show up in Explorer as they normally would — they'll just be decompressed on the fly at runtime. However, the newer algorithms are much more efficient than NTFS (LZNT1).
By default, the program runs Compact with the /EXE:XPRESS8K flag active. This provides a good balance between compression speed and size reduction. The default that Windows uses is /EXE:XPRESS4K.
The options available are:
- XPRESS4K: Fastest, but doesn't compress as much
- XPRESS8K: Decent balance between speed and compression
- XPRESS16K: Slower, but compresses the most
- LZX: Technically this one compresses the most, BUT is not recommended for programs and games as the overhead is higher
In my testing, using any of the XPRESS modes has no discernible impact on CPU performance when the compressed program is run (Using an i7-6700HQ). Here's the output tests for Adobe Photoshop:
However, if your processor is especially old, you may find that performance is worse when folders are compressed with 8K and 16K. Use 4K instead. Despite this, I've successfully tested it on an i3-370M from 2010, and it had no issues with performance on any of the compression modes.