How to Use File Compression in Windows - dummies

By Dan Gookin

Windows comes with a file compression feature. It’s an on-the-fly type of compression that stores files on a disk in a smaller size. When you open the file, it’s decompressed to its original size. So, as a user, you don’t notice the compression in any way other than that your files consume less disk space.

The compressed files are listed in the folder window with blue text rather than black. Here’s how to compress a file:

  1. Right-click the file or folder icon to compress.

    When you compress a folder, you compress all files and folders held in that folder. It’s a simple way to compress a slew of files all at once.

  2. Choose Properties from the shortcut menu.

  3. On the General tab of the Properties dialog box, click the Advanced button.

    The Advanced Attributes dialog box appears.


  4. Place a check mark by the option Compress Contents to Save Disk Space.

  5. Click OK, and then click OK again to dismiss the Properties dialog box.

You see the name of the file or folder displayed in blue text when it’s compressed. Beyond that, there aren’t really any changes; the file can still be manipulated or opened as it was before. It does, however, take up less space on disk.

Compression, however, isn’t a magic lozenge for curing a cramped hard drive. That’s because only certain files compress well.

For example, text files can be smooshed down to become quite small. Windows Bitmap files (BMP) compress well. Most of the files on your hard drive, however, are probably already in a compressed state. Therefore, they don’t benefit from additional compression. In fact, by compressing them, you might make your computer run slower because of all the overhead required to decompress the file on the fly.

  • To remove compression from a file, repeat the preceding steps, but in Step 4 remove the check mark.

  • An option in the Windows XP version of the Disk Cleanup program lets you compress seldom-used files. It’s another way to automatically reduce the file size of the documents and whatnot that you seldom use.

  • The encryption attribute is available only on NTFS-formatted hard drives.

  • You can also archive files into a compressed folder, which takes up less space. For seldom-used files, create a compressed folder and move the files into it. Although this method compresses the files, keep in mind that you cannot open a file stored in a compressed folder, nor does the Windows Search command find files (or their contents) inside a compressed folder.