Is Microsoft Defender enough? What the lab scores say

For a Windows PC, Defender is enough for most people. The labs don't show a protection gap between it and the paid suites. What they show is a small gap in performance, and a long list of extras you may or may not want.

What the labs found

AV-TEST's Microsoft page (checked Nov 1, 2026) lists Defender Antivirus (Consumer) 4.18 at 6 out of 6 for protection in every round from October 2024 through August 2026. That's 12 rounds in a row.

The latest round ran July and August 2026 on Windows 11, with 15 home products. Defender scored 6 for protection, 5.5 for performance and 6 for usability. Bitdefender Total Security 27.0 scored 6, 6 and 6. Norton 360, Avast Free and Malwarebytes Premium also got 6 across the board.

So Bitdefender beats Defender by half a point on performance, which is the only difference between the two in that round. AV-TEST's performance score covers how much the product slows the machine down. A half point is not a reason to spend money.

AV-Comparatives' Consumer Real-World Protection Test for February to May 2026 covered 20 home products. Seven earned its top award, Advanced+: Avast, AVG, Bitdefender, Kaspersky, Microsoft, Norton and TotalAV. Defender and Bitdefender are in the same tier. The page says products with high false-alarm rates had their awards adjusted, so a top award takes more than detection.

What Defender actually is

Microsoft's support page describes Windows Security as an app that brings together Microsoft Defender Antivirus, Windows Firewall and Smart App Control. It says Defender Antivirus "continuously scans your device for potential threats."

It's built into Windows. There's nothing to buy and no renewal date.

Windows only, though. The Defender entry here lists Windows. If you also run a Mac or an Android phone, the comparison changes: see best antivirus for Mac.

What paying adds

Not detection, going by the numbers above. Extras.

Bitdefender's Total Security page lists a password manager, a VPN and ransomware protection. The VPN is capped at 200 MB per day. Total Security Individual is $59.99 for the first year and covers up to 5 devices; Bitdefender says renewal "may be higher" and doesn't give the figure. The cheaper Antivirus Plus is $2.50 a month billed yearly, which is $29.99 for the first year and 3 devices. Both are first-year prices.

You can buy a password manager and a VPN separately. See best password managers and best VPN for those.

What a lab score can't tell you

Labs run malware against a clean machine, many times, under fixed rules. They measure the product. They don't measure you clicking Allow on a fake invoice, or reusing one password on 30 sites.

That's my opinion, not a lab finding, and it cuts both ways. An antivirus won't fix that behavior, and a free one doesn't make it worse.

When to pay anyway

Three cases. You want one product across Windows, Mac and phones. You want a family dashboard. Or you'd just rather not rely on one company for both the operating system and its protection.

The head-to-head is in Microsoft Defender vs Bitdefender. If ransomware is your worry specifically, ransomware protection for a home PC covers it. And Bitdefender against Norton is the renewal-price story.

The product entry for Microsoft Defender has the checked specs.