Microsoft Defender vs Avast

In this side-by-side comparison, I’ve put Microsoft Defender up against Avast Antivirus. I’ll compare the good and the bad to give you a clearer picture of which provider meets your requirements.

Microsoft Defender is included with Windows, accounting for over 1.5 billion users. Avast is also a heavy hitter, protecting 425 million devices worldwide. I’ve run a series of tests to understand how each impacts system performance, how easy they are to use, and the detection results produced when they face live virus samples.

Just want a quick answer? I can tell you that Avast is victorious. While Microsoft Defender is suitable for basic protection, Avast goes the extra mile to provide an all-in-one security solution. Aside from essential malware detection, Avast protects your webcam from hijacking attempts, blocks spam, etc. Avast also offers excellent discounts for first-year sign-ups.

Ready for the full comparison? Keep reading.

Microsoft Defender vs Avast summary

Microsoft Defender

  • Completely free
  • Included with Windows OS
  • Parental control options


  • Strong malware protection scores
  • Webcam protection
  • Automatically updates apps
No valueMicrosoft DefenderAvast One
Ransomware protection
Webcam protection
Password ManagerWindows Hello!
Web protection/anti phishing
Banking and Payment Protection
Network Attack Protection
Secure data encryption
Automatically update apps
File Shredder
Performance Optimization
Best deal (per month)Free
FREE download
GET 66% off 2 year plans

BEST DEAL FOR MICROSOFT DEFENDER:Pay nothing for Microsoft Defender as it comes preinstalled when you buy a Windows PC.

BEST DEAL FOR AVAST:Save 50% on Avast One and benefit from a wealth of security features for your device.


Microsoft Defender

Microsoft Defender, owned by Microsoft in the US, forms part of the Windows Security portfolio for Windows 10 and Windows 11 devices. The software has been around since 2001 as a free antivirus download with Windows XP, but the product available today incorporates a much broader range of features.

Microsoft Defender has undergone several name changes to get to where it is today, including Windows Defender and Windows Defender Antivirus in previous Windows versions.


Avast is among some of the most popular antivirus brands worldwide, operating its headquarters out of the Czech Republic since 1998 and having a global reach of 425 million users (according to recent data).

Avast joined forces with AVG in 2016, another well-known antivirus provider, enabling the company to combine the best of both products to detect and tackle some of the most sophisticated cyber security threats to date.

Microsoft Defender vs Avast pricing

Microsoft Defender gets a pass for this category because it doesn’t offer any pricing levels. It’s free, and that’s it! It comes included when you purchase a computer with Windows 10 or Windows 11 pre-installed. If you upgrade from an earlier OS, you’ll also have it included – although the Microsoft Defender is a piece of the more extensive Windows Security suite.

In other words, no downloads, no installation, no setup. Simple!

For those who need more sophisticated protection from Microsoft, there is a product for corporate customers called Microsoft Defender for Endpoint. This product isn’t aimed at consumers but rather at those with large networks that need a Microsoft Security expert ready to intervene when cyberattacks are too challenging for the software to handle alone.

No valueMicrosoft DefenderAvast One
One year priceFree$39.99
Renewal priceN/A$69.99
Best deal (per month)Free
FREE download
GET 66% off 2 year plans

Meanwhile, Avast offers a much broader range of subscription levels ranging from free protection to security for up to 30 devices. Avast One free is the most popular product for users who only need a basic level of protection. Considering it doesn’t cost anything, Avast One Free gives users a great range of tools beyond malware and virus detection, such as a VPN to protect your privacy, online banking protection, leaked password monitoring, and tools to optimize system performance.

While these features will bolster your online and offline security, the free version of Avast does come with limitations, i.e., usage on a single device and a 5 GB weekly data cap for its VPN – which you’ll likely use up streaming a few shows on Netflix.

The next level of protection offered by Avast is Avast Premium Security. First-year users can get the software for $39.99, and this price then creeps up to $69.99 after the first twelve months. Aside from standard malware and virus protection, Avast Premium Security protects you from fake websites by redirecting you to a secure website when it detects a malicious URL. It also includes ransomware protection that checks for brute force login attempts and patches OS vulnerabilities to prevent RDP exploits attacks. Like its base plan, you’ll get protection on a single device.

Avast Premium Security for up to ten simultaneous device installs will set users back $49.99 for the first year before increasing to $69.99 thereafter. The features of this plan are the same as the previous pricing tier except for the higher device limit.

Next up is Avast One Individual, which comes in at $50.28 for the first twelve months, and then goes up to $99.99 after that. Unlike Avast one Free, this plan includes unlimited VPN usage, advanced performance optimization tools, online tracking prevention, a smart firewall, and alerts about data breaches. You can install Avast one individual on up to five devices using one account.

Avast One Family offers the same features as the individual plan, but you’ll get six accounts that allow you to install the software on up to thirty devices at once. The family plan costs $69.48 for first-year sign-ups and then rises to $139.99.

All of Avast’s subscriptions include a 30-day money-back guarantee, enabling you to get a refund if you’re not entirely satisfied with the features or service.

Unlike Microsoft Defender, which only protects Windows devices, Avast has apps to protect Windows, macOS, iOS, and Android.

Effectiveness against malware

Antivirus and antimalware software should be up to detecting and blocking threats downloaded from the internet and existing threats lurking in the file directories on your device. To ensure Microsoft Defender and Avast One were capable of protecting my PC, I ran some tests to see how well they’d perform.

I used malware samples provided by the EICAR (The European Institute for Computer Antivirus Research) consisting of an executable file, a .txt file, and two zipped executables. The samples provided by the EICAR are used for lab testing, but I placed them in a sandbox environment to protect my system.

My tests also consisted of live virus and malware samples, including two trojans and one adware file. Both of these were compressed executables.

Real-time test

No valueMicrosoft DefenderAvast One
Eicar Sample 1BlockedAllowed
Eicar Sample 2BlockedAllowed
Eicar Sample 3BlockedAllowed
Eicar Sample 4BlockedAllowed
Live Sample 1 (Adware)BlockedBlocked
Live Sample 2 (Trojan)BlockedBlocked
Live Sample 3 (Trojan)BlockedBlocked
Best deal (per month)Free
FREE download
GET 66% off 2 year plans

I began with a real-time detection test that puts the software in a state of always-on scanning. For this test, I would expect to be notified by the software when the malware samples are downloaded, showing a threat is detected.

Unlike most antivirus apps, Microsoft Defender and Avast One can run in unison, with Windows Security disabling many of its own security features to allow the third-party software to function.

Microsoft Defender was up first, detecting and blocking every malware sample when I downloaded them. I had to unzip the fourth EICAR sample for the software to recognize it, but Microsoft Defender stopped it successfully.

I then enabled real-time detection for Avast One, which didn’t perform as well. It missed the compressed and unzipped EICAR samples and the .txt sample. However, it blocked all live samples and one of the EICAR samples.

On-demand scan results (quick)

I disabled real-time scanning for both software providers and ran a quick scan with each. Both antivirus products missed all of the samples during this scan.

On-demand scan results (full)

My final malware tests were full scans of my system. Avast One detected every malware sample (EICAR and live) and blocked the threats, which is odd considering it didn’t recognize them during the real-time tests.Avast eicar test

In contrast, Microsoft Defender blocked only one of the EICAR samples and allowed all live samples – which doesn’t make sense considering it blocked every threat in real-time.

I wanted to back up my research with the findings of some of the most extensive virus testing labs globally, AV-Comparatives, and AV-Test, to understand how the providers performed on a broader scale.

AV-Comparatives perform several different types of tests every year to benchmark antivirus providers, but there are only two I’m interested in at this stage, Malware Protection Test and the Real World Protection Test.

The Real World Protection Test measures how antivirus products stand up against threats on the internet and malicious websites.

In contrast, the Malware Protection Test looks at how well antivirus products perform when looking for offline malware threats that already exist on a system or threats introduced via a USB drive and checks whether they quarantine them.


One of the most recent real-world protection tests between July and October 2021 from AV-Comparatives put malware detection software up against 743 malware test cases.

Microsoft Defender achieved a 99.7% detection rate after blocking 741 test samples. It didn’t produce any false positives, i.e., detecting a legitimate file, website, or app that should have instead been allowed.

Avast One also performed remarkably during this test, detecting 742 threats to achieve a 99.9 percent protection rate, with just two false positives.


In September and October 2021, AV-Test scored Microsoft Defender 100 percent for protection against 0-day malware attacks, including web and e-mail threats. For detection of widespread malware discovered in the last four weeks, it scored 99.9 percent in September 2021 and 100% in October 2021.

In contrast, Avast scored 100% in both detection categories for September and October 2021.

This aligns with the detection rates performed in my own tests where Avast picked up all of the threats during on-demand scanning – making it the clear winner of this category.

Impact on PC performance

Antivirus software uses resources in your computer to complete on-demand scans, during background scanning, and while keeping malware databases updated with the latest definitions. I used Windows Performance Monitor to monitor my CPU usage, disk usage, and memory to see how Microsoft Defender and Avast One impacted my PC performance.

No valueMicrosoft DefenderAvast One
Full Scan Time (minutes)18660
Number of scanned objects3028231870000
Quick Scan CPU Utilization %6432
Quick Scan Memory Utilization %N/A72
Quick Scan Disk Utilization %88300
Quick Scan Time (seconds)1919
Best deal (per month)Free
FREE download
GET 66% off 2 year plans

Microsoft Defender completed a full scan in an hour, scanning 302,823 files, whereas Avast took a lengthier 186 minutes but scanned 1870000 – over five times as many as its rival. While speed is important, I would prefer a test that goes into more depth of my system to check for underlying threats, which would explain the number of threats detected by Avast versus Microsoft defender in my malware scanning tests.

The table below shows the impact on my PC while the software runs in the background. Avast One used significantly more control resources than Microsoft Defender, which is expected considering it forms part of the Windows OS rather than a third-party app.

No valueMicrosoft DefenderAvast One
Control CPU Utliization % (no scan)6464
Control Memory Utilization % (no scan)N/A72
Control Disk Utilization (seconds) (no scan)328
Full Scan CPU Utilization %10042
Full Scan Memory Utilization %N/A73
Full Scan Disk Utilization (seconds)3005801
Best deal (per month)Free
FREE download
GET 66% off 2 year plans

Likewise, Microsoft Defender was lower than Avast for disk and memory utilization during full scans, although it spiked higher than Avast for CPU utilization.

To compare my results, I researched the performance benchmarks available from AV-Comparatives. For context, AV-Comparatives takes the following categories into account when testing antivirus performance:

  • Downloading files
  • Browsing websites
  • File Copying: first and subsequent run
  • Installing and uninstalling applications
  • Archiving and unarchiving
  • Launching applications: first and subsequent run

In October 2021, Microsoft Defender performed well in every category except on the file copying category for first-run tests and unarchiving/archiving. In contrast, Avast did slightly better, with the only hiccup being a slowdown when launching applications.

Microsoft Defender vs Avast Features

Antivirus software often does much more than detecting and blocking viruses and goes extra lengths to protect aspects of your digital life. Check out the features below that are included with each provider.

Microsoft Defender

  • Antivirus and antimalware
  • Ransomware Protection
  • OneDrive Cloud Backup 5 GB
  • Windows Hello
  • Microsoft Family Safety
  • App and browser control

Avast Premium Security

  • Block malware
  • Safely run suspicious apps
  • Permanently shred sensitive files
  • Secure passwords
  • Block spam and phishing emails
  • Safer shopping
  • Webcam protection
  • Lock out hackers with an advanced firewall
  • Scan for wi-fi security weaknesses
  • Get an extra layer of ransomware security
  • Automatically update apps
  • Install on all your devices

Check out some of the key features of each provider below:

Microsoft Defender

  • Windows Hello: You’ll never need to remember your Windows password again, thanks to Windows Hello! Use biometrics like fingerprints or face recognition instead of long and hard-to-remember passwords across all of your Windows devices.
  • Microsoft Family Safety: Microsoft’s answer to parental controls keeps your family safe online from websites not meant for younger audiences and helps you to keep track of what everyone is getting up to online.
  • OneDrive Cloud backup 5 GB: Windows Security keeps your precious files and folder backed up to the cloud, so if your device fails or gets stolen, you can restore the backup and never lose access to your files.

Avast Premium Security

  • Install on all your devices: Avast lets you install protection across your favorite devices, meaning your computer, smartphone, and tablet benefit from robust security at home or on the go.
  • Webcam protection: Keep your webcam safe from hackers looking to hijack your device for blackmailing. Choose when your webcam is powered up and the apps that have access to it for watertight security.
  • Permanently shred sensitive files: When files are sent to your recycle bin, they are retrievable by cybercriminals looking to exploit your data. Use Avast’s file shredder and remove all traces of your deleted files.

Sign up & Installation

Signing up to Microsoft Defender isn’t at all necessary as it’ll automatically be ready when you install Windows. You could argue that there are settings to tweak to enable some of its features, such as ransomware protection (not enabled by default), but there’s no signup or installation.

On the other hand, Avast Premium Security requires you to complete checkout – much like you would for any purchase. It’s a straightforward process, and you should note that your subscription will automatically renew after twelve months upon signup.

I tested their 30-day money-back guarantee to see how easy it was to get a refund, and after contacting support, my refund was issued the next working day. Downloading the software was fast and straightforward, and the installation was completed quickly, letting me run a scan within five minutes of downloading the software.

How easy is the interface to use?

It’s one thing to have a good performing antivirus that doesn’t slow down your system, but I also wanted something simple to use and didn’t make me jump through hoops to perform the tasks I needed.

Microsoft Defender provides a basic interface that looks clean and is easy to navigate. Windows Security (the broader Microsoft Defender suite) is accessible from the Update and Security tab of Windows 10 and 11 settings.Windows Security at a glance

Upon accessing Windows Security, you’ll be provided with your security options at a glance, showing everything that’s working well in green, alerts in amber, and threats or priority actions with a red warning.

You can drill down into the features such as Virus and Threat protection which allows you to run quick or full scans, access scan history, and decide what to do with detected malware.

Family options lets you tweak settings related to Microsoft Family safety, such as the devices they’re using, the sites they access, and the time they spend online.

Avast premium Security is a more feature-packed user interface that combines a simple interface for beginner users with options for advanced users looking to take their security to another level.

You’ll see an overview of your AV protection from the main dashboard to let you know if things are going well or whether you need to act on anything.Avast interface

On the left, you’ll find a list of additional features that help perform different software functions beyond antivirus scanning. I was a new Avast user and found it super easy to use.

Customer Support

It’s important that you have support when things don’t go as planned with any software, and this is especially vital when you’re dealing with the prospect of a cyberthreat.

The support available with Microsoft Defender is quite limited, only giving the option of posting on the Microsoft Community forums. The support is much greater for those using Microsoft Defender for Endpoint, giving you an on-hand Microsoft engineer ready to deal with all queries no matter the complexity.

Avast One includes a much broader range of support options for subscribers of its premium product offerings. If you prefer to speak to someone over the phone, phone support isn’t an option, but if you’re okay with LiveChat when you need it and email support, Avast ticks all the right boxes.

Avast has a wealth of sources in its knowledgebase that answer most of the common questions for less urgent queries.

Microsoft Defender vs Avast conclusion

If you missed the winner at the start of this article, let me give you a gentle reminder. Avast Premium Security takes the crown from Microsoft Defender. Avast performed better in the depth of its on-demand scans and detection rates. It also provides many more helpful features to protect your online security than its competitors, like an unlimited VPN, a file shredder, and webcam protection.

Avast also has excellent customer support when you need it and offers some fantastic first-year discounts for new users.

Antivirus FAQs

Is Avast safe?

Yes, Avast premium Security and its other security products are 100% safe. Along with its antivirus and malware detection tools, its software goes to extra lengths to protect you online and your system from offline threats.

Is Avast necessary on a Mac?

We'd recommend installing a product like Avast One on your Mac to enhance your security. Although Macs have better security than Windows devices, and many believe that Macs aren't susceptible to virus threats, research has shown that macOS devices are still exposed to malware.

Do I need to use a VPN?

Although VPNs aren't mandatory, Virtual private networks bolster your online privacy by shielding your browsing activities, your files, and the apps you use on the internet. VPNs let you watch the content you already pay for at home from anywhere worldwide and help to beat heavy internet censorship in places like Russia and China. For these reasons, we'd recommend using a VPN to enhance your online protection.