Windows 8 disk space usage vs Windows 7

The official Microsoft Windows 8 (64 bit) disk space requirements are the same as Windows 7: 20 GB.

In actual practice, how does Win8's disk space usage compare to Win7's? Specifically, how does disk space usage compare after a clean install of each? I'm thinking the new Metro stuff must take additional space, but MS could have slimmed down the rest of Windows at the same time.

The Test

To try and make a fair comparison, I went for Windows 7 Ultimate SP1 versus Windows 8 Enterprise. Both editions were 64-bit. These are the most full-featured editions of the respective operating systems available, so could be considered as a "worst-case scenario". SP-1 was already slipstreamed into the Windows 7 Ultimate ISO, as supplied by Microsoft via TechNet.

The test consisted of two identically specified Virtual Machines running on Hyper-V - 1024MB of RAM was specified, and no network adapter was connected (to avoid auto-activation or any automatic updates). The systems were each installed onto newly created VHDs, the default options were chosen, and the first user account was created by setup (named Fred, both times if you're interested). As soon as it reached the desktop, the system was immediately shut down.

The Results

The VHD's were mounted as read-only into my main OS, and the properties for each were brought up.

Windows 7 Ultimate SP1:

Windows 8 Enterprise:

The Conclusion

Windows 8 Enterprise takes 3.38% more space than Windows 7 Ultimate SP-1.

Other Interesting Points To Note

On a blank hard disk, Windows 7 will create a System Reserved partition of 100MB, whereas Windows 8 will make it 350MB:

WinDirStat from the host computer onto the mounted VHD's gives the following output (drive F is Windows 7, H is Windows 8):

WinDirStat run on the Windows 7 VM gives:

WinDirStat run on the Windows 8 VM gives:

I took the plunge and installed Windows 8. Before installing Windows 8, I installed Windows 7 for a controlled comparison. Quick answer: both Windows 7 and 8 consume similar disk space, a little over 17 GB.

The exact answer depends on how Windows 7 and 8 compute file/disk sizes. Windows 8 simultaneously consumes less space and leaves less free space than Windows 7. In addition, Windows 8 reports a total disk size that is nearly a gigabyte smaller (on the exact same hardware) Percentage-wise, all the numbers are almost exactly the same:

           GB used       GB free       GB total  
Windows 8  17.3 (27.9%)  44.8 (72.1%)  62.1 (100%)   
Windows 7  17.6 (27.9%)  45.4 (72.1%)  63.0 (100%)

Methodology:

• Both installations were done on the exact same hardware, preceded by a clean format of the entire drive
• Windows 8 version: Windows 8 Pro 64-bit
• Windows 7 version: Windows 7 Ultimate with SP 1 64-bit
• Interestingly, Windows 7's required system reserved partition is 100 MB while Windows 8's is 350 MB
• Used/free space numbers taken from WinDirStat

Windows 8 results:

Windows 7 results:

After instaling Windows 8 Enterprise on VMBox - 11 GB (explorer)

I remember that after installing windows 7 it was much less space, around 7 GB!

In my experience Windows 8 is comparable in size to Windows 7.

After doing an upgrade of Windows 7 Ultimate, Windows.old was 21GB. After installing some Windows Updates on Windows 8 Pro, C:\Windows is 19GB.

Two months later of regular everyday usage, it has grown to 22.5GB. I think the main culprit is WinSXS.

That 22.5GB doesn't include Metro style apps (C:\Program Files\WindowsApps).