When dealing with archive files and compressed files, a distinction is often made between the Compressed Size and the uncompressed size of the file. Compression is used to decrease the file size of one or several files. The Compressed Size denotes the accumulated size of all compressed files inside the archive as well as the size of the archive itself. Thus, the Compressed Size is the end-result of the compression and shows how much space the archive and its content take up on your hard drive or other storage medium.
Depending on the compression method used, the Compressed Size differs more or less from the uncompressed size of the files. Some methods compress files more efficiently than others, resulting in a better saving of space.
The value is typically given in bites.