Is Windows Defender Good Enough in 2018?

When it comes to antivirus software, Windows Defender is the natural choice. In fact, it’s not so much a choice as just the standard state of things, as it comes pre-packed with Windows 10. (In previous Windows iterations it was known as Microsoft Security Essentials.) It’s therefore tempting to just leave it as is and say to yourself that things will probably be fine, right?

But is Windows’ built-in tool enough, or do we still need to rely on the big guns of anti-virus software to keep us safe online? Read on for the lowdown.

This analysis is based on Windows Defender 4.8 and tests carried out in April 2018. Results will inevitably vary over time, but we’ll be doing our best to keep on top of them.

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.


As of April 2018, Windows Defender has scored 5.5 across the three categories. That technically gives it the same “Protection” and “Performance” ratings as antivirus giants like Avast and AVG. It’s worth noting that, at the time of writing, the only anti-virus software to get full marks across the board are AhnLab Internet Security and Avira.

In real terms, according to AV Test, Windows Defender currently offers 100% protection against zero-day malware attacks, slows down web browsing by just 4% (against an industry average of 10%), and out of 1.6 million samples, detected just four legitimate bits of software as malware (industry average is 10).

So Windows Defender is certainly capable of mixing it up with the big boys, which may come as a surprise to those who knew of it several years ago as a somewhat rudimentary solution.

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?


Looking at the real-world protection tests, the results are again pretty good. AV Comparatives carried out its tests using a mix of malicious URLs, drive-by downloads, and URLs redirecting users to malware. Windows Defender had a 0% compromise rate, which was better than the 0.4% rates with Avast and AVG, and up there with the flawless scores of Avira, Bitdefender and McAfee.

Windows Defender even picked up the bronze award for false positives, coming in third place in terms of clocking up the least false detection of malware, which we probably all know from experience can cause a whole load of stress.

What Windows Defender didn’t do so well in (the worst out of all the tested antiviruses, in fact), was “user-dependent” malware. In 3.6% of malware instances, Windows Defender gives users the option to execute the malware rather than outright blocking it.

While this is of course better than just failing to detect it – as several of the tested anti-viruses did – it still means you need to be cautious and heed Defender’s warnings when it prompts you.

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. That has been almost directly replaced by the possibility of “user-dependent” security compromises in 2018, which still isn’t perfect but a huge improvement.

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.


However, if you want to err on the side of caution, there would be no harm in adding an extra layer of protection over Windows Defender, just to eliminate the minute possibility that something could sneak through the net.

But 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.

This article was first published in February 2017 and was updated in June 2018.

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