The chkdsk (Check Disk) utility is a built-in Windows command that scans hard drives for file system errors, bad sectors, and corrupt data, then repairs them.
Run it from Command Prompt as Administrator, via File Explorer drive properties, or the Windows Recovery Environment when your PC cannot boot normally.
Quick Answer
Open Command Prompt as Administrator and run chkdsk C: /f /r — Windows schedules the scan for the next restart since the C: drive cannot be locked while in use.
How to Use chkdsk on Windows
Method 1: Run chkdsk via Command Prompt
Open Start, search for cmd, right-click Command Prompt, and select Run as administrator to open an elevated terminal window.
Read-Only Scan (No Flags)
Running chkdsk with no flags performs a read-only scan — it lists errors found on the current drive without making any changes or attempting repairs.
chkdskFix Logical Errors: chkdsk /f
The /f flag fixes logical file system errors. On the C: drive, Windows cannot lock the volume while running, so it schedules the repair for the next restart.
chkdsk C: /f
Fix Bad Sectors: chkdsk /r
The /r flag locates bad sectors and recovers readable data from them. It includes all /f functionality and adds two extra scan stages for bad cluster detection.
chkdsk C: /rFor a different drive — for example D: — replace the letter: chkdsk D: /f /r scans and fixes both logical errors and bad sectors on that volume.
When chkdsk /r runs, it adds two stages beyond the standard three: Stage 4 scans for bad clusters in user file data, and Stage 5 checks for bad free clusters.
Force Dismount: chkdsk /x
Use /x when chkdsk returns “Cannot lock current drive” — it forces a dismount of the volume and then runs /f automatically to fix the errors found.
chkdsk D: /xOnline Scan Without Unmounting: chkdsk /scan
The /scan flag runs an online scan without unmounting the drive — ideal for non-system volumes that are actively in use by other programs at the time.
chkdsk D: /scan
Add /perf with /scan to use more CPU and complete the scan faster — close other programs first since this option is resource-intensive by design.
chkdsk /scan /perf
Note: The /scan /perf combination works on NTFS volumes only. It will not run on FAT32 or exFAT formatted drives.
Offline Scan and Fix: chkdsk /offlinescanandfix
Use /offlinescanandfix when /scan detects errors it cannot repair online — this schedules a full offline repair pass to run at the next system restart.
chkdsk /offlinescanandfix
To cancel a scheduled chkdsk before the next restart, run the command below and type N when prompted — this unschedules the pending repair immediately.
chkntfs /x C:Method 2: Run chkdsk via File Explorer
File Explorer provides a GUI way to run a basic chkdsk scan without opening a terminal — right-click any drive and access the check tool through its Properties dialog.
Step 1: Open File Explorer, click This PC, right-click the drive you want to check, and choose Properties (or press Alt + Enter after selecting it).
Step 2: Select the Tools tab and click the Check button under Error Checking, then click Scan drive to start the process.
The GUI scan runs in three stages: file record verification, index validation, and security descriptor authentication — each checking a different layer of the file system.
Click Show Details after the scan completes to open Event Viewer and review the full log of everything chkdsk found and fixed on the selected drive.
Method 3: Run chkdsk via Windows Recovery Environment (WinRE)
Use WinRE when Windows cannot boot due to severe disk corruption — it lets you run chkdsk against the system drive before the OS attempts to load at all.
Step 1: Boot from a Windows installation USB or DVD and click Repair your computer instead of Install Now on the first setup screen that appears.
Step 2: Navigate to Troubleshoot ? Advanced options ? Command Prompt to open a terminal that runs completely outside the Windows environment.
Step 3: Run chkdsk C: /f /r to scan and repair the C: drive. Replace C: with the correct letter if Windows is installed on a different volume.
chkdsk Flags Quick Reference
Here are the most useful chkdsk flags and what each one does — combine them as needed for more thorough scans and repairs on any Windows drive format.
| Flag | What It Does |
|---|---|
/f |
Fixes file system errors on the specified volume |
/r |
Locates bad sectors and recovers readable data (includes /f) |
/x |
Forces a dismount before running /f — use when drive is locked |
/scan |
Runs an online scan without unmounting the volume |
/perf |
Uses more CPU to speed up /scan (NTFS volumes only) |
/offlinescanandfix |
Schedules an offline repair when /scan finds unfixable errors |
When chkdsk Is the Right Tool
Run chkdsk when your PC boots slowly, blue screens mention file system errors, a drive shows warnings in File Explorer, or files become inaccessible unexpectedly.
It is also the right fix after an unexpected power outage or forced shutdown — Windows marks the drive as “dirty,” and chkdsk clears that flag after a clean scan pass.
For preventive maintenance, run chkdsk D: /scan monthly on secondary drives to catch developing errors before they escalate into data loss or full drive failure.
If chkdsk repeatedly finds the same errors on every scan, the physical drive hardware may be failing — back up your data and plan to replace the drive promptly.
Related Guides
These Windows maintenance and command-line guides cover tools that work alongside chkdsk for a complete system health check and troubleshooting workflow.