Compress Windows to save disk space with this hidden feature

Get more disk space by compressing files, folders and Windows

Is the Windows folder on the disk drive growing with each update or is it shrinking? It depends on whether this secret compression feature is turned on. Learn how to enable and disable it.

Save disk space on your Windows PC by using these compression techniques. Use the Compact command to compress Windows operating system files.

While Apple has raced ahead and has put solid state disks into all the company’s laptops, most Windows laptops still use old style mechanical disks. The advantages are that they are cheap and have a large capacity. The disadvantage is speed and they are terribly slow compared to SSDs.

However some Windows laptops do have SSDs and this raises storage issues. They are small and it is very easy to run out of disk space. What can be done to maximise the space available to software, documents music, photos and videos?

Of course, it is not just laptops with SSDs that have storage problems and some budget laptops and even desktop PCs, have disks of only a few hundred gigabytes. If you have an old budget desktop or laptop PC, you could be struggling for disk space.

The answer is file compression and it can be achieved in several ways.

Related: How to compress images to make your website faster

Zip your files

Zipping files is the worst option. Right click one or more files or folders and select Send to, Compressed (zipped) folder. It creates a zip file named after the file or folder that was right clicked and the original files can then be deleted.

This is OK for emailing files to someone across the internet, but it is useless for files you frequently use. In addition to this, it is not possible to zip Windows itself, so no savings can be made in the Windows folder.

Use NTFS compression

Windows is able to automatically compress files on the fly as it writes them to disk and when they are accessed, they are automatically decompressed in real-time too. It is totally transparent compression and compressed files and folders look perfectly normal and work in every way just like uncompressed ones.

This makes it a useful option to use and a fair bit of disk space can be recovered by converting ordinary files and folders into NTFS compressed ones. To apply NTFS compression:

  1. Right click a file or folder in Explorer or on the desktop and select properties on the menu
  2. Click the Advanced button
  3. Tick the option to Compress contents to save space
  4. Click OK, OK
  5. When asked, apply the change to this folder and all subfolders

Compress files and folders in Windows

Compression is quick with one file, but it could take several minutes with a folder full of files and subfolders. Afterwards the file and folder icons in Explorer have a tiny double headed arrow in the top right corner to indicate that they are compressed. This is easier to see if the Explorer view is set to large icons.

Files and folders that have been compressed with NTFS compression

It is possible to compress the contents of the whole disk in this way.

  1. In an Explorer window, select This PC in the sidebar
  2. Right click the C: drive and select Properties
  3. Tick the checkbox Compress this drive to save disk space

Compress the disk contents in Windows

It could take an hour or more, so do it when you are not busy.

Use the Windows 10 Compact tool

There is a little known Compact utility in Windows 10 that can be run from the command line. Right click the Start button and select Command Prompt (admin) from the menu. In the command window, type:

compact /?

This displays all the command's functions (adding /? to most commands displays help). The Compact command can be used to compress individual files and folders, but that isn't what interests us most. Down at the bottom of the help listing is /CompactOs. This is used to compact operating system files - Windows in other words.

To compact the Windows folder, you would type:

compact /CompactOs:always

By compressing Windows operating system files, several gigabytes of disk space can be saved. To see this, right click the C:\Windows folder in an Explorer window and select Properties.

Windows folder properties showing the disk space used

Compare the figure for the size of the folder and the size on disk. The amount of disk space used is nearly 6GB less than the actual size of the files on the disk

This is a considerable saving of disk space. It could make a significant different to the way Windows runs on a PC that is nearly out of disk space.

Is Windows compressed on your PC?

Check the Windows folder size by right clicking it and selecting Properties as shown above, or use the Compact command like this:

compact /CompactOs:query

Windows Compact command showing whether the OS is compressed

Does this compression affect performance?

On the one hand, compressing and decompressing files takes time and processing power, but on the other hand time is saved because less data is read from the disk. It therefore probably doesn’t make a lot of difference and gains balance losses.

You can try it both ways and to remove the compression from the operating system files, type:

compact /CompactOs:never

All Windows operating system files will be decompressed. Is your PC any faster or is there no difference. If it runs just the same, you may as well turn on compression again.

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1 Comment on Compress Windows to save disk space with this hidden feature

  1. I actually really need to do this!

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