To scan for viruses on Windows 10, open Windows Security (search for it in the Start menu), click Virus & threat protection, and click Quick scan. For a deeper check, click Scan options, choose Full scan or Microsoft Defender Offline scan, and click Scan now. Microsoft Defender Antivirus is built into Windows 10 and free.
Below you’ll learn which scan to use, how to scan a single file or USB drive, what to do if something’s found, and how to fix a scan that won’t run.
Which scan should you run?
| Scan | What it checks | Time |
|---|---|---|
| Quick scan | Places where threats usually hide | A few minutes |
| Full scan | Every file and running program | An hour or more |
| Custom scan | Only the folders or drives you choose | Varies |
| Microsoft Defender Offline scan | Restarts and scans before Windows loads, to catch hard-to-remove malware | About 15 minutes |
How to run a quick scan
- Click Start, type Windows Security, and open it.
- Click Virus & threat protection.
- Click Quick scan.
How to run a full or offline scan
- In Virus & threat protection, click Scan options.
- Choose Full scan, Custom scan, or Microsoft Defender Offline scan.
- Click Scan now. For an offline scan, save your work first, because your PC restarts.
How to scan a file, folder, or USB drive
Right-click the item in File Explorer and choose Scan with Microsoft Defender. Results appear in Windows Security.
What to do if a threat is found
- Click Start actions or review the threat under Current threats. Defender usually quarantines or removes it automatically.
- Run a Full scan or Microsoft Defender Offline scan to check for anything left behind.
- Change passwords for important accounts from a clean device if you suspect your information was exposed.
- Review Protection history to see what was found and what action was taken.
Keep protection up to date
- Make sure Real-time protection is on under Virus & threat protection settings > Manage settings.
- Click Check for updates under Virus & threat protection updates to get the latest definitions.
- Windows 10 reached end of support in October 2025. Defender definitions may continue for a while, but the operating system itself only gets security fixes through Extended Security Updates.
Troubleshooting
- “Your virus and threat protection is managed by your organization”: Your IT department controls Defender. Contact them.
- Another antivirus is installed: Defender turns off its real-time protection when another antivirus is active. Use that program to scan, or uninstall it to use Defender.
- Windows Security won’t open: Update Windows, then run sfc /scannow in an admin Command Prompt.
Frequently asked questions
Is Windows Defender enough?
For most home users, Microsoft Defender provides solid protection when combined with updates and safe browsing habits.
How often should I run a full scan?
Defender scans in the background automatically. Run a full scan if your PC acts strangely or after a suspicious download.
Can I scan for viruses from the command line?
Yes. Run “%ProgramFiles%\Windows Defender\MpCmdRun.exe” -Scan -ScanType 1 for a quick scan, or -ScanType 2 for a full scan.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.