Microsoft Defender comes bundled with every copy of Windows 10 and 11 and requires no payment or subscription to use. And over the years, it has slowly evolved into a powerful antivirus tool that's well worth using.

Running a full scan with Microsoft Defender regularly is recommended, but if you only need to check a single file or a single folder, a custom scan gets the job done much faster. Here's how to use Microsoft Defender's custom scan to check a single file or folder.

How to Scan a Single File or Folder With Microsoft Defender

Microsoft Defender comes with several types of antivirus scans; Quick, Full, and Custom. Microsoft doesn't make it immediately obvious what a custom scan is and what it can do. However, custom scans are perfect if you want to do a targeted scan on a file or folder. Here's how:

  1. Open the Start menu and click the cog icon to open Settings.
  2. Click on Update & Security, then Windows Security on the left.
  3. Click on Virus & Threat protection, which will open a new window. Click Scan options in this window.
  4. Select Custom scan and then click the Scan now button. An Explorer window will open, allowing you to navigate to the folder you want to check.
    Screenshot of Microsoft Defender custom scan
  5. You won't see individual files listed in the window, but as long as you know where your file is located, you can just select that folder or drive location.
  6. When you click the Select Folder button, scanning will automatically begin. Everything in the folder will be scanned, including any sub-folders. Even so, a single folder scan should take just a few seconds.

Custom scans are just a small part of what makes Microsoft Defender a great antivirus tool. Recent antivirus test scores from AV-Test prove just how reliable the built-in Windows security tools are.

Microsoft Defender's Custom Scans, Made Easy

Although Quick scans usually don't take more than a few minutes, being able to scan just a single folder or a single file within a folder is a handy option. Windows Security offers a great range of protection for your computer, and exploring to see what else it can do is worth your time.