Your C: drive is nearly full, and a large part of it is OneDrive. You may not remember choosing to keep those files on this PC.
What OneDrive is doing
OneDrive has a feature called Files On-Demand. With it, every file shows up in File Explorer, but files you are not using are online-only: they are in the cloud and do not take up space on your PC. [R1]
A file stops being online-only when:
- you open it. The file does not download until you open it. [R1]
- you mark it "Always keep on this device". These files are downloaded and take up space, but are available even when you are offline. [R1]
- an app asks for it. Some apps download online-only files on their own, for example a music player fetching music to play. [R2]
So OneDrive may fill the disk without any single big decision. A backup tool, a photo app or a search indexer reading through a folder can pull down a lot.
How to tell which files are using the space
In File Explorer, open your OneDrive folder and look at the Status icons:
- A cloud means online-only and costs no space. [R1]
- A green circle with a white tick means "Always keep on this device". [R1]
Right-click a large folder, and choose Properties to compare Size with Size on disk. A big gap means most of it is online-only.
Step 1: Turn copies back into online-only files
Right-click a file or folder in OneDrive and choose Free up space. The file stays in the cloud and in File Explorer, but its copy on your PC is removed.
What this costs. You need an internet connection to open it again. Do not use it for files you need when you are offline, such as documents for a trip.
Do this for the biggest folders first. Folders you marked "Always keep on this device" will not shrink until you change that choice.
Step 2: Stop apps downloading on their own
When an app downloads online-only files, Windows shows a notification with where it is downloading from and how many files. [R2] If you do not want that, choose Cancel download, then Block app. That cancels the download and blocks the app from downloading online-only files again. [R2]
If you block an app by mistake, go to Settings > Privacy & security > Automatic file downloads to allow it again. [R2]
What blocking costs. The app may fail to open those files, or show errors when it tries.
Step 3: Pause sync while you sort it out
Right-click the OneDrive icon next to the clock and choose a pause time. Syncing resumes by itself when the pause is over, or you can resume it yourself at any time. [R3] OneDrive also pauses by itself in battery saver mode or on a metered network. [R3]
Pausing stops new downloads. It does not remove anything already on your disk.
If you used "Free up space" and the space did not come back
Check that OneDrive is running and is not paused, give it a little time, and then look at the free space again. If it still has not changed, restart OneDrive. Do not delete the files yourself to force it: deleting a file is not the same as freeing up its space.
What should I do now?
- Find the biggest OneDrive folders.
- Use Free up space on folders you do not need offline.
- Block any app that keeps downloading what you did not ask for.
- Pause sync if downloads are still arriving.
- Check free space again.
Kajlos can show how much of your OneDrive folder is on this disk and how much could be made online-only. It asks before it changes anything, and it never deletes your files.