What Is thumbs.db and How to Stop Windows Creating It

What's inside thumbs.db and where it comes from

thumbs.db is a small database Windows Explorer writes into a folder the first time you view it with thumbnails: it stores miniature previews of images and videos so reopening the folder feels instant. The design dates back to Windows 2000/XP, when Explorer kept the cache next to the pictures. Since Vista the main cache lives centrally in %LocalAppData%\Microsoft\Windows\Explorer (the thumbcache files), which is why you rarely see thumbs.db on ordinary local folders today.

The exceptions are exactly where people meet it. Network shares and NAS folders, where a central cache makes no sense, still get their thumbs.db, and so does any directory that got zipped, synced or backed up while Windows still wrote its cache there. The file carries hidden and system attributes, so it only shows up after you enable showing hidden files — usually at the worst moment, inside a backup or a git repository.

• A thumbnail-sized copy of each image and video, packed in a binary database
• Hidden + system attributes — invisible until you enable showing hidden files
• Recreated automatically whenever you reopen the folder in thumbnail view
• Most often seen on network shares, NAS folders and inside synced or zipped directories
• Harmless to Windows — but it pollutes backups, archives and version control

Deleting it safely and stopping the re-creation

Deleting thumbs.db is safe: it's a pure cache, and Explorer rebuilds it if it ever needs it again. Close the folder (and any preview window) first — Explorer locks the file while the folder is open — then delete it with hidden files visible or from the command line. On network shares, close all Explorer windows pointing at the folder.

To stop Windows writing thumbs.db at all, Pro and Enterprise editions have a policy for it: run gpedit.msc, go to User Configuration → Administrative Templates → Windows Components → File Explorer, and enable "Turn off the caching of thumbnails in hidden thumbs.db files". On Home editions the same switch can be set with a one-line registry edit, or you can kill thumbnails globally in Folder Options → "Always show icons, never thumbnails" — a real trade-off, since you lose previews everywhere. If you just want existing files gone across the disk in one pass, a cleanup tool like Kleaner PRO finds and removes every thumbs.db without you hunting folders manually.

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