How to Run a Virus Scan with Windows Defender
Windows Defender is your PC's built-in antivirus — here's how to run a manual scan and check your protection status.
4 min read · 6 steps · Checked April 2026
Step 1. Open Windows Security
Click the Start button (Windows icon at the bottom left of your screen) or press the Windows key on your keyboard. Type "Windows Security" and press Enter. The Windows Security dashboard will open — this is where all of your PC's protection settings live.
Step 2. Check your protection status
Look at the colored icons on the dashboard. Green checkmarks mean everything is working normally. A yellow or red icon means something needs attention — click on it to see what action is needed. The most important category is "Virus & threat protection."
Quick Tip
If you see a message that protection is off, click the "Turn on" button to re-enable it. Defender should always be running unless you have a separate antivirus program installed.
Step 3. Run a Quick Scan
Click "Virus & threat protection." The screen shows when the last scan ran. Click "Quick scan" to start scanning right away. A quick scan usually takes 2 to 10 minutes and checks the most common locations where threats appear — your running processes, startup files, and common system folders.
Step 4. Run a Full Scan for a thorough check
Click "Scan options" on the Virus & threat protection screen, select "Full scan," and click "Scan now." A full scan checks every file on your computer and takes 30 minutes to an hour or longer. You can continue using your computer during the scan, though it may run a little slower.
Step 5. Review any threats found
If Defender finds something suspicious, it will notify you and quarantine the file automatically. Click "Protection history" to see a list of items that were detected and quarantined. In most cases, Defender has already handled the threat. You do not need to take additional action unless prompted.
Warning
If Defender finds a threat it cannot handle automatically, it will ask you to decide what to do. "Remove" is the safest choice for anything flagged as a virus or malware.
Step 6. Check that automatic updates are on
Go back to the Virus & threat protection screen and look for "Virus & threat protection updates." Click "Check for updates" to make sure your definition files are current. Defender updates automatically on most systems, but checking manually after a period of no internet access is a good habit.
Windows Defender — now officially called Microsoft Defender Antivirus — is a free antivirus and security program built into every Windows 10 and Windows 11 computer. You do not need to buy or download anything extra. It runs automatically in the background and scans new files as they arrive. But you can also run a manual scan at any time to check your computer for threats.
Many Windows users are not aware that Defender is running because it works quietly in the background without interrupting you. It updates its list of known viruses and malware every day (as long as your PC has internet access), which is how it stays current against new threats.
To check your protection status or run a manual scan, click the Start button (the Windows icon in the lower left of your screen), type "Windows Security," and press Enter. This opens the Windows Security dashboard — a central hub for all your computer's protection tools.
On the main dashboard, you will see colored circles for different protection categories. Green checkmarks mean everything is working normally. A yellow exclamation mark means something needs your attention. A red X means a protection feature is off or there is a threat to address.
To run a scan, click "Virus & threat protection." This screen shows the date of your last scan and lets you choose between scan types. A Quick Scan takes a few minutes and checks the areas where threats are most commonly found. A Full Scan takes longer (often 30 to 60 minutes on a typical PC) but checks every file on your computer. Run a Quick Scan first — if any problems are found, Defender will prompt you about next steps.
When Defender finds a threat, it moves the suspicious file to a quarantine area automatically. You can review quarantined items under "Protection History." For most users, the default action (quarantine) is the right choice, and Defender handles it without needing your involvement.
If you have a third-party antivirus program installed — like Norton, McAfee, or Bitdefender — Windows will usually disable Defender automatically to avoid conflicts. You do not need both running at the same time.
Official sources
- Microsoft Support — support.microsoft.com
- Windows Help — support.microsoft.com
- Microsoft 365 Help — support.microsoft.com
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