Difference in size between File History backup and C: drive?

Big Swifty

Jul 13, 2016
New to PC's and Windows. Just used File History to backup my files for the first time.

There is now 370 gb of data on my external drive (which sounds about right, considering I only brought over photos, music, and a very small amount of documents when I transferred over from my old Mac).

There is 540 gb of data on my internal C: drive.

What is included in the 170 gb of data not copied to my external drive? I've read that Windows 10 takes up about 20 gb of space, but that still leaves 150 gb.


Aug 3, 2013
If you right click on the Windows 10 start button, select Control Panel, and type 'file history' in the search bar, you are taken to the relevant page if you click on the first result. In the bottom left hand corner of the File History page, you are also given the option of creating a System Image, or creating a System Repair Disc. So that's three options in total.

File History does not back up Windows or software installations. All this itself would take up far more than 20gb. Even windows 7 alone after all important system updates can take up over 40GB, so I expect similar from 10. Add your own manually installed software and over time it can expand to well over 100GB quite easily. Also consider temporary files such as old updates lying dormant in hidden folders within the system that are no longer needed-so windows can expand to a fair size. ps Updates on 10 seem to be fewer, but larger, maximum of around 3GB each (such as the latest 'anniversary update').

File History regularly backs up versions of your files in the Documents, Music, Pictures, Videos, and Desktop folders and any OneDrive files available offline on your PC. Over time, you'll have a complete history of your files. If the originals are lost, damaged, or deleted, you can restore them. You can also browse and restore different versions of your files. For example, if you want to restore an older version of a file (even if it wasn't deleted or lost), you can browse through a timeline list, select the version you want, and restore it. File History has the option to select specific folders to include or ignore, and how often you want windows to create backups. Make sure you do not exclude important folders.

System Image creates a full backup of windows which will include the operating system and all related files, user profiles and documents. Having an emergency System Image on another drive can come in handy in the advent of a power/drive failure, or malware that corrupts the windows system and 'file history' fails to work. There are third party tools such as paragon system backup and recovery that do a similar job, but can backup your hard drive completely. Third party tools such as this one may be more useful if windows does not see other partitions eg for someone running both linux and windows on the same drive, or make it simpler to clone your current windows to a new larger hard drive, for the same computer.

System Repair Disk simply gives you the option to create a repair disc to fix an already existing but problematic installation of windows.