External Drive Used Space Wrong – File Sizes Don't Add Up

Quick answer

Enable hidden files in File Explorer, empty the Recycle Bin on the drive, and run Disk Cleanup as Administrator to delete volume shadow copies.

What's actually happening here

You plug in your external drive, right-click Properties, and it says you've used, say, 500 GB. But when you select all folders inside, right-click Properties, the total is only 350 GB. That 150 GB gap drives people crazy. I've seen this on WD My Passport, Seagate Backup Plus, and even SSDs. The reason step 3 works is that Windows doesn't show you everything by default.

The three usual suspects are:

• Hidden system files – like System Volume Information, $Recycle.Bin, or $RECYCLE.BIN. Windows hides these on purpose because messing with them can break things.
• Recycle Bin data – when you delete files from your external drive, they go to a hidden Recycle Bin folder on that same drive. Emptying your desktop Recycle Bin doesn't touch it.
• Volume Shadow Copies (also called Previous Versions) – System Restore or backup software can store snapshots of files on the drive. These don't show up in normal file listings.

Step-by-step fix

I'll give you the exact steps. Skip the fluff.

1. Show hidden files
   Open File Explorer. Click View tab. Check Hidden items. Also uncheck Hide protected operating system files (you'll get a warning – click Yes).
   Now you'll see folders like $Recycle.Bin and System Volume Information. You can't delete System Volume Information directly – that's normal.
2. Empty the external drive's Recycle Bin
   Open a Command Prompt as Administrator. Type rd /s X:\$Recycle.Bin where X is your drive letter. Press Enter and confirm. This deletes that hidden folder and all its contents. It's safe – Windows recreates it automatically.
3. Delete Volume Shadow Copies
   This is the one that recovers the most space. Run Command Prompt as Administrator. Type vssadmin list shadows /for=X: (replace X with your drive letter). You'll see entries like Shadow Copy Volume: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy12. To delete all shadows on that drive: vssadmin delete shadows /for=X: /all. Confirm with Y.
   On Windows 10/11, you can also use Settings > System > Storage > Configure Storage Sense (or Cleanup recommendations) and check Previous versions of files – but the command line is faster and more reliable.
4. Run Disk Cleanup
   Right-click the drive in File Explorer, choose Properties, click Disk Cleanup. It scans for temporary files, thumbnails, and Recycle Bin. Check all boxes, especially Temporary files and Recycle Bin. Hit OK.
5. Check for hidden large files
   Use a tool like WinDirStat or TreeSize Free. These scan the drive and show every byte in a visual map. You'll spot any weird large files or folders you forgot about.

If the main fix doesn't work

Sometimes the difference is still there after steps 1–5. Here's what else to try:

• Check for pagefile.sys or hiberfil.sys – these giant system files can appear on external drives if you ever enabled System Restore or virtual memory on them. Look for pagefile.sys and hiberfil.sys in the root of the drive (after showing hidden files). If you see them, move your pagefile settings in System Properties > Advanced > Performance.
• Run chkdsk – filesystem errors can report wrong used space. Open Command Prompt as Admin, type chkdsk X: /f. It'll fix any logical errors. This won't recover space directly but makes the numbers honest.
• Format and restore from backup – if nothing works and you absolutely need the space back, copy your files elsewhere, format the drive (quick format is fine), then copy back. This guarantees you start clean.

A practical example

Friend of mine had a 2 TB Seagate drive that showed 1.2 TB used. Total of visible files was 800 GB. That's a 400 GB gap. Running vssadmin delete shadows freed 350 GB. The rest was from the Recycle Bin folder. After both, the numbers matched within 2 GB (filesystem overhead).

Prevention – stop it from happening again

Three things:

1. Turn off System Restore for external drives – Open System Properties > System Protection. Select your external drive, click Configure, and choose Disable system protection. This prevents Windows from saving shadow copies there.
2. Don't enable indexing on external drives – go to drive Properties, uncheck Allow files on this drive to have contents indexed. Indexing creates hidden database files that eat space.
3. Empty Recycle Bin specifically for the external drive – don't just use the desktop Recycle Bin. Right-click the Recycle Bin icon, choose Properties, select your external drive tab, and set Custom size to 0 MB. Then, when you delete files from that drive, they skip the Recycle Bin entirely.

That's it. You now know why the numbers lie and how to fix it.