Check Disk scans your hard drive for errors and can repair them automatically

Check Disk (also called chkdsk) is a Windows tool that scans your hard drive or external drive for file system errors and bad sectors. It can find problems like corrupted files, lost clusters, and physical damage to the drive itself. You can run it through Windows Settings with a few clicks, or use the Command Prompt for more control over what gets checked and repaired.

The tool works in two stages: it first scans for logical errors (problems with how files are organized), then optionally scans for physical errors (damage to the drive hardware itself). Depending on which version you use and what options you choose, the scan can take anywhere from a few minutes to several hours for a large drive.

Key Takeaways

  • You can run Check Disk through Settings on Windows 10 and 11, or through Command Prompt for older versions or advanced options.
  • The tool requires administrator access and will ask to schedule a scan before your next restart if the drive is currently in use.
  • Running a full scan with repair on your main Windows drive requires a restart and will take time — plan for this when your computer is not needed.
  • External drives and secondary drives can be scanned and repaired without restarting, making them faster to check.
  • Check Disk is most useful after a crash, if you see file errors, or if a drive is making unusual sounds or running slowly.

Running Check Disk through Windows Settings (Windows 10 and 11)

Open Settings and go to System > Storage. Find the drive you want to check and click on it. Select Advanced options, then click Check. Windows will scan the drive for errors. If it finds any, it will offer to repair them — click Repair to proceed.

If you are checking your main C: drive (the one Windows is installed on), Windows will tell you the scan must happen before the next restart. Click Scan and repair drive to schedule it. Your computer will restart, run the scan, and return to the login screen when finished. This can take 10 minutes to several hours depending on drive size and how many errors exist.

For external drives or secondary internal drives, the scan runs immediately without a restart. You can continue using your computer while it works, though performance may slow down slightly.

Running Check Disk from Command Prompt (all Windows versions)

Open Command Prompt as administrator. Right-click the Start menu, select Terminal (Admin) or Command Prompt (Admin), and click Yes when asked for permission. Type the command and press Enter.

The basic command is chkdsk C: (replace C: with the drive letter you want to check). This scans for errors but does not repair them. To repair errors, add /F at the end: chkdsk C: /F. To also scan for bad sectors on the drive hardware, add /R: chkdsk C: /R (this includes the /F repair option automatically).

If you are checking your main Windows drive, the system will ask to schedule the scan before the next restart. Type Y and press Enter, then restart your computer. The scan will run before Windows loads. If you are checking a different drive, the scan starts immediately.

Understanding the scan options and what they do

Check Disk has several modes. A basic scan with no options checks the file system structure — how Windows organizes files and folders — but does not fix problems. Adding /F tells it to repair errors it finds. Adding /R tells it to locate bad sectors (damaged areas of the drive) and recover readable data from them; this is slower but more thorough.

You can also use /X to force the drive to unmount (disconnect) before scanning, which is useful if Windows is locking the drive and preventing a scan. For external drives, you may need this option to get a complete scan.

The /V option shows verbose output — a detailed list of every file being checked. This is rarely necessary but can help if you are troubleshooting a specific file.

When to run Check Disk and what to expect

Run Check Disk if your computer crashed or shut down unexpectedly, if you see error messages about corrupted files, if a drive is making clicking or beeping sounds, or if a drive is running much slower than normal. You should also run it after a power failure or if you unplugged an external drive without safely ejecting it first.

A scan of a 1 TB drive with no errors typically takes 10 to 20 minutes. A scan with repair can take 30 minutes to an hour. A full scan including bad sector checking (/R) can take several hours. If Check Disk finds many errors, the repair process will take longer.

After the scan completes, Check Disk will report how many errors it found and how many it repaired. If it repaired errors, your drive should run more smoothly. If it found bad sectors, those areas are marked as unusable so Windows will not try to write data there again.

What to do if Check Disk cannot complete or finds severe damage

If Check Disk keeps failing or cannot complete, the drive may have serious physical damage. Try running it again with the /R option to scan for bad sectors — this gives the tool more time to work around damaged areas. If it still fails, the drive hardware may be failing and may need replacement soon.

If Check Disk reports a very large number of bad sectors or cannot repair critical system files, back up your data immediately if possible and consider replacing the drive. A drive with widespread damage will eventually fail completely, and continuing to use it risks losing files.

If you see the error "The type of the file system is NTFS" or similar, the drive may be formatted in a way Check Disk does not recognize. This is rare on Windows systems but can happen with drives formatted on Mac or Linux. In this case, Check Disk cannot help, and you may need to reformat the drive or use a different tool.

Frequently Asked Questions

Can I use my computer while Check Disk is running?

On external or secondary drives, yes — the scan runs in the background and you can work normally, though performance will be slower. On your main C: drive, no — if you chose to repair errors, Windows schedules the scan before startup and your computer will restart. You cannot use it during the scan.

Will Check Disk delete my files?

Check Disk does not delete files intentionally. It repairs the file system structure and recovers data from damaged areas. In rare cases, if a file is too corrupted to repair, it may move the file to a folder called Found.000 on the drive root. You can then try to open or recover the file manually.

How often should I run Check Disk?

You do not need to run it regularly on a healthy drive. Run it only when you suspect a problem — after a crash, if you see error messages, or if the drive is behaving oddly. Running it unnecessarily does not harm the drive but wastes time.

What is the difference between Check Disk and Disk Defragmenter?

Check Disk finds and repairs errors in the file system and drive hardware. Disk Defragmenter reorganizes files on the drive to improve performance. They do different jobs — Check Disk fixes problems, Defragmenter optimizes speed. You may need both, but Check Disk is more urgent if errors exist.

Can I stop Check Disk once it starts?

If the scan is running before startup (on your main drive), you can press any key to stop it, but this is not recommended — let it finish so it can repair errors. If it is running in Windows on an external drive, you can close the window, but the scan will continue in the background. Interrupting a repair operation may leave the drive in an inconsistent state.