NTFS supports transparent file based compression. Compressed files may be read or written without having to be (de)compressed via an external program. Automatic decompression and compression is performed when reading or saving a file and comes at almost no extra cost.
Compressed files require less storage space than their uncompressed versions. Uncompressed files can be compressed by 40% to 60%, files using a compressed file format (such as ZIP or JPEG files) by 5% to 10%.
TreeSize displays a file or folder's true size on disk space in addition to its size. The compression ratio can be displayed in an extra column on the "Details" tab. In addition, compressed files and folders may be tagged in a different color (this function can be activated in the "Options") dialog. The same applies to sparse files, another special feature of the NTFS file system.
TreeSize offers one-click compression and decompression of whole directory trees. Simply choose the respective function in the context menu.