Do you need antivirus, or is Windows Defender enough?

Windows Defender is free, already on, and tests level with paid antivirus for most people. What the labs found, who should still pay, and how to cancel McAfee or get a Norton renewal refunded.

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There is a red banner in the corner of your screen. It says your antivirus subscription expired, and it has been saying so for a while now. You feel a little guilty every time you see it. Then you close the window and go back to what you were doing.

No need to feel guilty, the computer has been protected the whole time.

Windows 10 and Windows 11 both include Microsoft Defender Antivirus. It is on by default, it updates itself along with Windows, and it is not a trial that runs out. If you have been paying somebody else for an antivirus, you have been buying a second one.

What the research found

Three independent labs test antivirus software on Windows and publish the results for free. AV-TEST in Germany, AV-Comparatives in Austria, and SE Labs in the UK. They collect real malware, run it at real products on real machines, and score what happens. AV-Comparatives states that taking part in its public tests is free of charge, and Microsoft has been in those tests since 2007. Defender is measured against the same paid products on the same tests.

Here is the most recent round, checked in August 2026.

AV-TEST, May and June 2026. Sixteen home security products on Windows 11, all at their default settings. Defender caught 100 percent of the brand-new “zero-day” samples in both months (224 of them) and 100 percent of the 11,772 widespread samples. Perfect score for protection, perfect score for usability. They scored 5.5 out of 6 for performance, which cost it half a point and still earned the TOP PRODUCT award.

AV-Comparatives, February through May 2026. Twenty products, 400 live malicious websites. Kaspersky blocked 399. Bitdefender blocked 398. Avast, AVG and Norton blocked 397. Microsoft Defender blocked 396. Nobody blocked all 400, and it only takes one to ruin your week, so read that as a field that is close rather than a field that is finished. Four months of live threats separated first place from free by three websites.

That same test counts false alarms, meaning the times a product blocks something clean and harmless. Those matter, because a program that cries wolf teaches you to click past its warnings. Defender wrongly blocked zero clean files or sites, the best result of all twenty products. Total Defense was second with one, then ESET with two, then Kaspersky and VIPRE with three each. The average across the field was eight. Trend Micro blocked 83.

SE Labs, April through June 2026. Defender earned AAA, the top award, with 98 percent total accuracy, sitting alongside Kaspersky, McAfee, Sophos, Norton, Avast, Panda and Scanguard.

Where the paid products still win

The paid products do sometimes earn their place.

The paid products typically don’t need an internet connection to function. Defender leans hard on Microsoft’s cloud to check whether a file is dangerous. In AV-Comparatives’ March 2026 test of 10,000 malware samples, Defender’s online protection rate was 99.93 percent. Its offline detection rate was 89.2 percent. Bitdefender managed 97.6 percent offline, G DATA 97.8, F-Secure 98.6. If a machine spends any significant time off the internet, one of the paid options would be worth looking at.

They also do better against a targeted attack, which is a person working their way into one specific computer with hacking tools rather than malware sprayed at everybody at once. SE Labs builds those by hand and runs them at each product. Only Kaspersky and Malwarebytes stopped every one. Defender missed a few. So did most of the field.

Most home computers stay online, and almost nobody gets singled out by a person. Both gaps are still real, and any review claiming the free one wins on every measure has not read the tests.

Follow the money

So why does everything you find when you go looking say otherwise?

Start with the laptop. That trial in the corner of the screen is a paid placement. McAfee’s own annual report filed with the Securities and Exchange Commission spells it out. The company pre-installs a 30-day free trial with:

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To read the full article for free, go to www.freshfromcache.com/do-you-need-antivirus/

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