Is Windows Defender Good Enough in 2021?

Windows Defender Good Enough Featured

It’s slowly becoming less and less of a given that you need to pack your Windows 10 PC with all manner of antivirus software, firewalls and other security software to keep it safe from malware and other threats. Many people now just stick with Microsoft’s integrated security package, Windows Security (formerly known as Windows Defender), but does it do a comparable job to third-party software? Is it good enough in 2021?

To test this, we’ve gathered data from a few of the most rigorous antivirus testing sites to see how Windows Defender compares to the most popular third-party antivirus software. We’ve done this for a couple of years now so we can compare Windows Defender’s performance with how it did the previous year.

How Does Windows Defender Compare?

Talking about Windows Defender in isolation won’t get us anywhere. What we need to know is how it stacks up to the biggest antivirus programs that you’ve probably downloaded or even paid for over the years – the McAfees, AVGs and Bitdefenders of the world.

Thankfully, there are several sites dedicated to comparing antivirus software on a monthly basis.

AV Test

AV Test helps users make educated decisions about what antivirus they should use. They rank each antivirus on three factors using a scale from 0 to 6, where 6 is the best. The three elements they test for are protection, performance, and usability. So how did Windows Defender fare?

Pretty well, it seems.

Is Windows Defender Good Enough 2020 Av Tests

In December 2018, Windows Defender scored 6 for security and 5.5 for performance and usability. In December 2019, Windows Defender maintained its perfect security score, while bumping up its usability to full marks too. That’s a marked improvement, especially as out of the 18 AV apps tested, only three of them – Norton Security, Kaspersky, BullGuard – got full marks across the board.

In real terms, according to AV Test, Windows Defender currently offers 100-percent protection against zero-day malware attacks. It’s particularly improved by cutting down on false flags, confusing only two bits of legitimate software for malware. For perspective, the industry average is three, and this time last year Windows Defender detected seven.

There wasn’t even a huge amount of room for improvement from last year, but Windows Defender has managed it, now ranking among the best of the best antiviruses on this site.

AV Comparatives

It’s hardly representative to look at just one website, though, as AV Tests’ means of testing and criteria will differ slightly from another. On that note, another popular website for antivirus testing is AV Comparatives. Can Windows Defender carry its impressive form over to this site?

Is Windows Defender Good Enough 2020 Av Comparatives

Looking at the real-world protection tests, the results are very good, and crucially a solid improvement on the same results over last year. Windows Defender was this time just one of two antivirus software (alongside Avira) to not be compromised at all based on 703 test cases.

Windows Defender has continued its improvement in blocking “user-dependent” malware – so malware where Windows gives a warning to the user but still gives the option of executing it. In April 2018 the rate of user-dependent malware was 3.6%. In July through November 2018 this dropped down to an average of 0.8%, and now it’s improved just that little bit more to 0.7%

In compliance with AV Tests, Microsoft has registered vast improvements in avoiding false positives, but it’s still labouring quite a long way behind the pack here. Its 58 false positives are a big improvement on the 106 last year, but it still detects more than double the amount of false positives as the second-worst in this area. Better safe than sorry, we guess?

Much Better than It Used to Be

Small hiccups aside, historical data on both AV Test and AV Comparatives shows a marked improvement in Windows Defender’s performance over the years.


Back in October 2015, Windows Defender received the joint-lowest rating for Protection (3.5/6), amounting to just 95% protection against 0-day malware attacks. (This was an alarming 80.5% in September 2015.) The industry average at the time was 97.2%, so Windows Defender was decidedly trailing the pack.


At AV Comparatives, meanwhile, Windows Defender had a 3% compromise rate from July through November 2016. Given that it now has the rare achievement of not being compromised at all, this is an impressive improvement.

The Verdict: It’s All You Need

Just a few years ago you’d have been laughed off for suggesting that it was enough for you to sit back, install no third-party AV software, and let Windows take care of defending your PC. While we wouldn’t encourage complacency, Windows Defender is now well-proven as a viable antivirus option unto itself.


You can always be super-cautious and bolster Windows Defender with a good free antivirus like Avira, but with Windows Defender now ranking among the very best when it comes to security, then there probably isn’t much need. The only way in which it seems to lag behind is its speed/performance and false positives, which have no bearing on your security.

Do you need to worry if all you have is Windows Defender? No, not any more. However, the malware landscape is always shifting, and we’ll keep an eye out for developments that suggest otherwise.

Image credit: Businessman using shield safe protection with connections 3D ren by DepositPhotos

Robert Zak
Robert Zak

Content Manager at Make Tech Easier. Enjoys Android, Windows, and tinkering with retro console emulation to breaking point.

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