A file can be stored in the cloud and still occupy space on the PC. Sync tools keep selected files offline, cache streamed content, and sometimes retain temporary data while changes are uploaded.
Cloud storage is not automatically online-only
OneDrive Files On-Demand, Google Drive streaming, and iCloud optimized storage can leave placeholders for files that are not downloaded. Other files are kept locally so they open without an internet connection. Mirrored folders may keep complete local copies by design.
That is why the amount shown by a cloud provider, File Explorer, and a disk scan may not match. The useful number during a low-space incident is the allocated space currently present on this drive.
OneDrive has a safe Free up space path
SizeTrend's Overview pane can identify locally available OneDrive files on the scanned drive. The Free up space action keeps the file in OneDrive and changes the local copy to online-only. It will download again when opened.
The confirmation also warns that files explicitly marked Always keep on this device are included. Do not use Delete when your goal is only to recover local space, because deleting a synced file can also delete it from OneDrive.
Google Drive and iCloud need provider controls
SizeTrend groups recognized Google Drive and iCloud local storage for review. Google Drive may mirror files or cache streamed content. iCloud can keep Drive files and Photos downloaded for offline use.
Use the provider's streaming, offline-storage, or Free up space command. Removing synced files directly in Explorer can propagate the deletion to the cloud, which is very different from releasing a local cached copy.
Dropbox temporary cache is a separate case
Dropbox keeps recently deleted and temporary sync data under its hidden .dropbox.cache folder. SizeTrend can show that cache separately when it is large enough to matter.
Quit Dropbox and verify that syncing is complete before reviewing it. Dropbox normally clears temporary cache data over time, and SizeTrend does not remove those files automatically. Ordinary files in the Dropbox folder remain personal synced data.
Check sync status before changing anything
Make sure the provider has finished uploading recent changes and that you can see the files from another device or the provider's website. If the account is paused, signed out, or reporting an error, fix that first.
After freeing local space, refresh the scan. The online files still exist, but their allocated size on the PC should be much smaller until they are opened again.
Free local space without deleting the cloud copy.
SizeTrend separates locally available files, cloud-storage review, and temporary sync cache.