How to run Microsoft Defender full virus scan on Windows 11

Keeping your computer safe from viruses, ransomware, spyware, and other harmful software is one of the most important parts of using Windows 11. Even if you are careful about the websites you visit and the files you download, malware can still find its way onto your computer through email attachments, infected USB drives, fake software installers, or compromised websites.

Fortunately, Microsoft Defender Antivirus comes with Windows 11 and provides strong protection without requiring you to install additional antivirus software. While it constantly monitors your computer in the background through Real-Time Protection, there are times when manually running a Full Scan is the best option. A full scan carefully checks your entire computer, including system files, installed programs, documents, and other locations where malware commonly hides.

This guide explains everything you need to know about running a Microsoft Defender Full Virus Scan on Windows 11. 

What does a Microsoft Defender full scan do?

A Microsoft Defender Full Scan performs a thorough inspection of your computer instead of checking only the areas that are most likely to contain threats.

Unlike a Quick Scan, which usually finishes in a few minutes by scanning common malware locations, a Full Scan examines almost every accessible file on your computer. It checks your operating system files, installed applications, personal documents, downloads, external storage devices that are connected during the scan, and many other locations.

During the scan, Microsoft Defender compares files against its malware definitions, analyzes suspicious behavior, and checks for hidden threats. If it finds harmful software, it automatically alerts you and recommends actions such as quarantining or removing the infected file.

Although a full scan takes longer than a quick scan, it provides much greater confidence that your computer is free from malware.

Things to Do Before You Start

Before beginning the scan, there are a few simple preparations that can make the process smoother.

Make sure your computer is connected to a stable internet connection. Microsoft Defender regularly downloads the latest Security Intelligence Updates, allowing it to recognize newly discovered threats.

Save any open work and close unnecessary programs. Although you can continue using your computer during the scan, closing unused applications allows Microsoft Defender to scan files more efficiently.

If you have recently connected a USB drive or external hard drive and want it checked as well, leave it connected before starting the scan.

It is also a good idea to plug your laptop into a charger if the battery is running low because a full scan can take anywhere from several minutes to several hours depending on the size and speed of your storage.

How to Run a Microsoft Defender Full Virus Scan on Windows 11

Step 1: Open the Windows Security app

Click the Start button on the taskbar and type Windows Security into the search box.

When Windows Security appears in the search results, click it to open the application. This is the central location where Windows manages antivirus protection, firewall settings, account security, and device protection.

After the app opens, you will see several security categories on the main screen.

Step 2: Open Virus & Threat Protection

Inside Windows Security, click Virus & Threat Protection.

This page displays your current antivirus status, recent scan history, protection updates, and available scanning options. If Microsoft Defender is your primary antivirus, you will see that it is actively protecting your computer.

Take a moment to verify that there are no warning messages before continuing.

Step 3: Open Scan Options

Scroll down until you find the Current Threats section.

Click Scan options located below the Quick Scan button.

This page displays several scanning methods. Each option serves a different purpose depending on how thoroughly you want your computer examined.

Step 4: Select Full Scan

Choose Full Scan from the available scan types.

A Full Scan checks all files and running programs on your hard drive. Because it examines much more data than a Quick Scan, it usually takes significantly longer to complete.

Once the Full Scan option is selected, click Scan now.

Microsoft Defender immediately begins examining your computer.

Step 5: Allow the scan to finish

The scan progress appears on your screen along with the number of files that have already been checked.

Depending on your computer’s storage size, the scan may finish within 30 minutes or continue for several hours. Larger drives containing hundreds of thousands of files naturally require more time.

During the scan, avoid shutting down your computer. You may continue working, browsing the internet, or editing documents, although your computer may feel slightly slower while Defender is actively scanning files.

Step 6: Review the scan results

After the scan finishes, Microsoft Defender displays the final results.

If no threats are found, you will receive a confirmation that your computer is clean.

If suspicious files are detected, Windows Security provides recommendations for handling them. Carefully review the results before taking action.

You can also view recent scans by returning to the Virus & Threat Protection page and reviewing your Protection History.

What Things May Happen During the Scan?

While Microsoft Defender is performing a Full Scan, several normal events may occur.

Your computer may temporarily run slower because the antivirus is reading thousands of files stored on your drive. This is completely expected.

The cooling fan may spin faster as your processor works harder during the scan.

The scan progress may appear to pause at certain percentages. This usually happens when Defender is checking very large files or compressed archives. It does not necessarily mean the scan has frozen.

You may also receive notifications if Defender detects suspicious activity. If that happens, simply allow the scan to complete before reviewing the results.

Sometimes the estimated remaining time changes during the scan. This is normal because Windows continuously recalculates the workload as additional files are discovered.

What to Do if Microsoft Defender Finds Malware?

If Microsoft Defender detects malware, do not panic.

Windows Security usually recommends placing the infected file into Quarantine. Quarantined files are isolated so they cannot damage your computer or spread to other files.

After reviewing the detected threats, choose the recommended action. In most situations, allowing Microsoft Defender to quarantine or remove the threat is the safest choice.

Once the malware has been removed, restart your computer if Windows recommends doing so.

After restarting, perform another Full Scan to confirm that no additional threats remain.

If malware continues to appear after multiple scans, consider running a Microsoft Defender Offline Scan, which scans your computer before Windows fully starts. This helps remove stubborn malware that hides while Windows is running.

How to Run a Full Scan Using PowerShell

Advanced users can also start a Full Scan through Windows PowerShell.

First, click the Start button and search for PowerShell.

Right-click Windows PowerShell and select Run as administrator.

When the PowerShell window opens, type the following command:

Start-MpScan -ScanType FullScan

Press Enter.

Microsoft Defender immediately begins performing a Full Scan just as if it had been started through Windows Security.

You can leave the PowerShell window open until the scan finishes.

How to Run a Full Scan Using Command Prompt

You can also launch a Full Scan using Command Prompt.

Search for Command Prompt, then choose Run as administrator.

Enter the following command:

“%ProgramFiles%\Windows Defender\MpCmdRun.exe” -Scan -ScanType 2

Press Enter.

Microsoft Defender starts scanning your computer.

If your version of Windows stores Defender in a different location, Windows may automatically redirect the command to the correct executable.

How to Scan a Specific File, Folder, or Drive?

Sometimes you may only want to examine one downloaded file, an individual folder, or an external drive instead of scanning your entire computer.

Open File Explorer and locate the file, folder, or drive you want to inspect.

Right-click the item and choose Scan with Microsoft Defender.

Windows Security immediately begins checking only the selected item. This type of scan is much faster than a Full Scan because only the chosen location is examined.

After the scan finishes, Windows displays whether any threats were found.

How to Schedule a Microsoft Defender Full Scan?

If you want your computer to perform regular Full Scans automatically, you can create a scheduled task.

Open Task Scheduler by searching for it from the Start menu.

Navigate to Task Scheduler Library, then Microsoft, Windows, and finally Windows Defender.

Locate the task named Windows Defender Scheduled Scan.

Open its properties and switch to the Triggers tab.

Create a new trigger by choosing how often you want the scan to run, such as weekly or monthly, along with the preferred day and time.

Save the changes.

Your computer will now automatically perform Microsoft Defender scans according to the schedule you selected. For best results, choose a time when your computer is usually turned on but not heavily in use.

FAQs

Does a Full Scan delete my personal files?

No. Microsoft Defender only removes files that it identifies as malicious. Your personal documents, photos, and videos remain untouched unless they are actually infected.

How long does a Full Scan take?

The scan duration depends on your computer’s hardware, storage capacity, and the number of files stored on your system. It may take anywhere from 30 minutes to several hours.

Can I use my computer while the scan is running?

Yes. Windows 11 allows you to continue using your computer during the scan, although performance may temporarily decrease.

Should I run a Full Scan regularly?

Running a Full Scan once every few weeks or whenever you suspect suspicious activity is a good security practice.

Is Microsoft Defender enough for most users?

Yes. For most home users, Microsoft Defender Antivirus provides strong protection when combined with regular Windows updates and safe browsing habits.

What is the difference between a Quick Scan and a Full Scan?

A Quick Scan checks common malware locations, while a Full Scan examines almost every file and folder on your computer, making it much more comprehensive.

Summary

Running a Microsoft Defender Full Virus Scan is one of the easiest and most effective ways to keep your Windows 11 computer secure. While Real-Time Protection continuously monitors your system, a Full Scan provides a much deeper inspection by checking nearly every file, folder, and running program for malicious software.

By opening Windows Security, selecting Virus & Threat Protection, choosing Scan options, and starting a Full Scan, even first-time Windows users can thoroughly examine their computers for hidden threats. You can also launch the same scan through PowerShell or Command Prompt, scan individual files and folders when needed, or schedule automatic scans for ongoing protection.

Making Full Scans a regular part of your computer maintenance routine helps detect threats early, improves overall system security, and gives you greater peace of mind whenever you use your Windows 11 PC.