Windows 11 includes Microsoft Defender Antivirus in the Windows Security app. You can run a quick scan in seconds, a full scan for a deeper check, or an offline scan for stubborn threats.
Quick Answer
Open Start, type Windows Security, go to Virus and threat protection and click Quick scan. For a deeper check, click Scan options and choose Full scan or Microsoft Defender Offline scan.
How to Check for Malware on Windows 11
- Click Start, type Windows Security and open it.
- Select Virus and threat protection.
- Click Quick scan to check common locations.
- For a thorough check, click Scan options, choose Full scan and click Scan now.
- If you suspect a hidden threat, choose Microsoft Defender Offline scan. The PC restarts and scans before Windows loads.
- Review results in Protection history and follow the recommended actions.
Scan Types
| Scan | Use it when |
|---|---|
| Quick scan | Routine check (a few minutes) |
| Full scan | Something seems wrong (can take an hour or more) |
| Custom scan | Checking one folder or drive |
| Offline scan | Malware resists removal |
Related: adding a Defender exclusion safely.
Troubleshooting
- Scan button greyed out: another antivirus may be installed and in control. Scan with that product instead.
- Browser still shows pop-ups: reset the browser and remove unknown extensions.
- Signs of infection after scans: back up your files and consider resetting Windows.
- Related: testing files in Windows Sandbox and troubleshooting Windows 11.
Frequently Asked Questions
Is the built-in antivirus enough?
For most home users, Microsoft Defender plus updates and care with downloads gives good protection.
How often should I scan?
Defender scans automatically. Run a manual scan if something seems off.
Can I scan one file?
Yes. Right-click it and choose Scan with Microsoft Defender (under Show more options on some builds).
What about scam pop-ups?
Close the browser. Never call numbers shown in pop-ups.
Summary
- Open Windows Security.
- Go to Virus and threat protection.
- Run a Quick scan.
- Use Full or Offline scan if needed.
- Check Protection history.
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.