Is your Windows 11 PC acting strange — running slow, crashing, or showing suspicious pop-ups? These could be signs of a virus or malware infection. Luckily, Microsoft has built-in tools to help, and you can also use trusted third-party antivirus software for extra protection.
In this guide, we’ll show you step by step how to do a virus scan on Windows 11 using Windows Security (Microsoft Defender) and other antivirus options. By the end, you’ll know how to run quick scans, full scans, and advanced scans — plus how to stay protected in the future.
Why Virus Scans Are Important in Windows 11
Even though Windows 11 has stronger built-in security than previous versions, viruses and malware are constantly evolving. Running virus scans helps you:
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🛡 Protect personal data (banking info, passwords, photos).
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⚡ Improve performance by removing hidden malware.
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🖥 Prevent system crashes caused by malicious programs.
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🌐 Block hackers from gaining remote access.
Think of a virus scan like a health check-up for your PC — regular scans catch small problems before they become serious.
How to Know If Your PC Might Have a Virus
Not sure if you need to scan? Look for these warning signs:
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Slower performance than usual.
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Random pop-ups or ads (even when not browsing).
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Apps crashing or refusing to open.
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Unknown programs installed without your consent.
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High CPU/disk usage in Task Manager.
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Suspicious emails or messages being sent from your account.
If you notice any of these, it’s time to run a virus scan immediately.
Windows Security: Your Built-In Antivirus
Windows 11 comes with Windows Security (formerly Windows Defender) pre-installed. It provides real-time protection and different types of scans:
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Quick Scan → Checks key areas where threats often hide.
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Full Scan → Scans every file and program on your PC.
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Custom Scan → Lets you pick specific folders or drives to scan.
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Microsoft Defender Offline Scan → Boots before Windows starts to catch hard-to-remove malware.
Method 1: Run a Quick Scan in Windows 11
A quick scan is the fastest way to check your PC.
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Press Windows + I to open Settings.
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Go to Privacy & security → Windows Security → Virus & threat protection.
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In the new window, click Quick scan.
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Wait a few minutes while Windows checks common threat locations.
👉 Use this scan regularly (once a week) for routine safety.
Method 2: Run a Full Scan
If you suspect something serious, a full scan is more thorough.
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Open Windows Security (as in Method 1).
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Under Current threats, click Scan options.
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Select Full scan.
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Click Scan now.
This may take 30 minutes to several hours depending on your files.
Method 3: Run a Custom Scan
Need to check only a specific drive or folder?
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In Scan options, choose Custom scan.
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Click Scan now.
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Select the folder or drive you want scanned.
This is useful if you’ve just downloaded files from the internet and want to scan them before opening.
Method 4: Run an Offline Scan
Some malware hides so deeply it can’t be removed while Windows is running. That’s where an offline scan helps.
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Open Windows Security → Virus & threat protection.
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Click Scan options.
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Select Microsoft Defender Offline scan.
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Click Scan now.
Your PC will restart and scan before Windows loads — catching rootkits and persistent viruses.
Using Third-Party Antivirus Software
While Windows Security is solid, some users prefer extra layers of defense. Popular options include:
| Antivirus | Strengths | Free Version? |
|---|---|---|
| Avast | Lightweight, good for beginners | ✅ |
| Bitdefender | Excellent malware detection, minimal slowdown | ✅ |
| Kaspersky | Advanced features, strong threat database | ✅ (limited) |
| Norton | Comprehensive protection, includes VPN & backup | ❌ |
| Malwarebytes | Best for adware/spyware removal | ✅ |
👉 Pro Tip: Never run two real-time antivirus programs at the same time. It can cause conflicts.
How to Schedule Automatic Virus Scans
To make sure you never forget:
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Open Task Scheduler (search in Start).
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Click Create Basic Task.
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Name it “Scheduled Virus Scan.”
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Choose how often (daily/weekly).
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Under Action, select Start a Program.
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Type:
This sets up a scheduled full scan automatically.
How to Update Virus Definitions
Your antivirus is only as good as its latest update.
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Open Windows Security → Virus & threat protection.
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Under Virus & threat protection updates, click Check for updates.
Windows will download the newest definitions to detect the latest threats.
What to Do If a Virus Is Found
If a scan detects malware:
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Windows Security will show an alert.
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Options include:
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Quarantine → Moves the file to a safe area.
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Remove → Deletes the threat permanently.
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Allow on device → Only if you’re 100% sure it’s safe.
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👉 If the virus keeps coming back, run an Offline Scan or use a third-party malware removal tool.
Best Practices for Ongoing Protection
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Keep Windows Update enabled.
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Only download apps from Microsoft Store or trusted sites.
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Use a strong password and enable Windows Hello or 2FA.
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Don’t click suspicious links or email attachments.
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Run weekly Quick Scans and monthly Full Scans.
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Consider pairing Windows Security with Malwarebytes Free for spyware protection.
Conclusion
Running a virus scan on Windows 11 is quick, easy, and essential for keeping your system safe.
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Use Quick Scan for regular checks.
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Run a Full Scan or Offline Scan if you suspect infection.
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Keep virus definitions updated.
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Add third-party antivirus only if you need extra protection.
By following these steps, you’ll keep your PC healthy, secure, and running smoothly.
FAQs
1. Does Windows 11 need antivirus?
Yes, but Windows Security (Defender) is built-in and works well for most users.
2. How long does a virus scan take in Windows 11?
Quick scans take 5–15 minutes, while full scans can take several hours depending on file size.
3. Can I run two antivirus programs at once?
No — running two real-time antivirus apps causes conflicts. Stick with one main antivirus.
4. How do I know if my PC is infected?
Signs include slow performance, random pop-ups, high CPU usage, and unknown apps installed.
5. What’s the difference between a quick scan and a full scan?
Quick scans check common virus hiding spots, while full scans examine your entire system.
✅ Key Takeaway: You can easily do a virus scan in Windows 11 using Windows Security. Start with a quick scan, but don’t forget to run full scans and keep your definitions updated for maximum protection.