Avast! Free PC Antivirus Review

Antivirus protection is a must-have on a Windows PC, but many people aren't willing, or able, to pay for a yearly subscription. Enter Avast Free Antivirus. Developed by Czech security company Avast!, the software offers protection from malware threats both widespread and cutting edge, as well as other computer security features. But how does it stack up to the other free competition?

MORE: Best Free Antivirus Software

Setup and interface

Installing Avast Free Antivirus is easy. We simply opened up a Web browser, went to www.avast.com, scrolled down to the "Essential Avast! Free Antivirus" section, and clicked the "Download" button.

Once the installation completed, an alert appeared informing us that our Avast software's spyware protection was out of date. We updated it.

The next step is to set up an Avast account by clicking the "Register" button at the top of the screen. You'll see a page that recommends upgrading to Avast's "complete protection" antivirus suite, which costs $49.99 per year.

This page isn't terribly pushy, merely showing you which extra features the full suite offers. By way of contrast, AVG Antivirus Free has all sorts of little reminders to upgrade inserted in its features, while Avira Free Antivirus very rarely nags users to upgrade to its premium version.

We were then offered a 20-day free trial of Internet Security, another of Avast's paid security programs. For the purposes of this review, we declined the trial by clicking "Stay with basic protection." The whole installation and setup process took about 10 minutes.

Avast's Free Antivirus sports a clean and useful interface. Its backbone is a gray menu column running down the left-hand side that lists various features.

The topmost feature, Status, serves as the program's home screen. It displays the computer's protection status, whether other programs are up to date and whether its active antimalware protection (called "Shields") is working.

The Status page also has quick-launch buttons labeled Quick Scan, Browser Cleanup and Free Mobile Security. Users can add or remove other quick-launch buttons.

Features and tools

In addition to quick scans and full scans, you also have the option to scan attached storage devices, such as USB sticks or external hard drives, with the "Removable media scan" feature, or to scan a single folder with "Select folder to scan."

You can schedule a boot-time scan with Avast Free PC AV. The next time your computer restarts, Avast will pause the Windows OS load, drop into a DOS-like text screen and scan the operating system for rootkits and other types of malware that are difficult to extricate from a running Windows system.

Aside from detecting already-installed malware, Avast protects your computer from getting infected in the first place with File System Shield, Web Shield and Mail Shield. File System Shields scans programs as you use them; Web Shield scans the URLs you visit in your browser and blocks URLs it considers dangerous; and Mail Shield scans your mail for malicious links and attachments.

AVG Antivirus Free is the only other free suite we reviewed that had similar features.

Avast Free Antivirus also comes with other tools. These include Software Updater, which shows you major programs installed on your computer and whether they are fully updated. With it, you can confidently ignore phony browser pop-ups that claim some of your downloaded programs are out of date. 

Then there's "Browser Cleanup," which checks installed Web browsers (Chrome, Firefox, Internet Explorer or Opera and/or Safari) for unwanted toolbars and other potentially unwanted or malicious browser extensions. You can set this to run regularly, or initiate a manual cleanup.

Another tool, called "Access Anywhere," lets other Avast users access your computer with your permission, to help you solve any tech issues you may have.

Finally there's "Rescue Disk," which lets you create a bootable CD or USB with Avast's virus definitions on it. With such a disk, you can do offline virus detection, and manually move the latest virus definitions to a computer not connected to the Internet.

A virtual-private-network tool called SecureLine is also listed under "Tools," but it requires a separate paid subscription.

Beneath the Tools button on the left-hand menu is another feature called "My Devices," which lets users manage other computers and mobile devices running Avast's software. Only Avira and AVG also have mobile products, and of their free Windows offerings, only Avira offers a built-in mobile center (AVG's is a separate download).

See our review of Avast’s Android antivirus protection.

Security performance

How good are Avast Free Antivirus’ malware-detecting chops? German independent lab AV-TEST tested the software's ability to catch widespread as well as newly appeared malware threats. An April 2014 test found that Avast Free Antivirus was able to detect 94 percent of zero-day (previously unknown) malware attacks from both the Web and email, which is the industry average.

Avast was also able to detect 98 percent of what AV-TEST calls "widespread and prevalent" malware, more than the industry average of 96 percent.

This puts Avast Free Antivirus in third place among the free antivirus programs we've reviewed. Avira is in first place, with perfect scores in both zero-day and widespread malware (AV-TEST actually evaluated a paid Avira product that uses the same malware scanner), followed by AVG Antivirus Free, finding 96 percent of zero-day malware and 99 percent of widespread malware. 

Windows Defender is a distant fourth, detecting only 68 percent of zero-day malware and 79 percent of widespread malware. Malwarebytes does not submit its products to AV-TEST, and therefore we cannot compare its Anti-Malware Free to the other brands.

APRIL 2014

Zero-Day Malware

Widespread Malware

Avast Free Antivirus



Avira Internet Security



AVG Antivirus Free



Windows Defender



Malwarebytes Anti-Malware



Industry Average



System Impact

The ideal antimalware program would perform scans in the background, and only alert you to its presence when it detected a problem. Unfortunately, most products do cause PCs to slow down, at least a bit while they perform their scans.

To gauge Avast's impact, we first installed the PCMark7 performance benchmark on an Acer Aspire E1 laptop with a Core i3 processor and 4 GB of RAM, the same machine we used to test all other antimalware products. Before any security software was installed, this laptop scored a baseline of 2,105 on PCBenchmark7.

While Avast's quick scan was running, the PCMark7 score dropped to 1,746. While running Avast's full scan, the score dropped further, to 1,664. That puts Avast in last in terms of quick-scan performance, and second-to-last (after Avira) in terms of full-scan scores. However, the performance impact shouldn't be too noticeable unless you're streaming video or playing a video game. You may not even notice the impact if you're using a high-end PC.

We conducted a second performance check using our custom OpenOffice test, which matches 20,000 names and addresses. When a scan wasn't running, the Acer Aspire E1 completed this task in 4 minutes.

When Avast's quick scan was running, the custom test completed in 9 minutes and 28 seconds. When the full scan ran, the task took 9 minutes and 6 seconds. This was the only instance among our system tests in which the quick scan had a higher performance impact than the full scan.

On the quick scan, Avast fared worse than Avira and Windows Defender. Its time on the full scan while running our OpenOffice test was slightly behind AVG but better than Avira, Malwarebytes and Windows Defender.

PCMark7 Quick Scan

PCMbuark7 Full Scan

Custom Test Quick Scan

Custom Test Full Scan

Avast Free Antivirus





Avira Free Antivirus





AVG Antivirus Free





Windows Defender





Malwarebytes Anti-Malware






Avast's less-than-perfect (but still decent) malware-detection scores and notable system impact while running quick scans might turn users away. But Avast's great interface and light performance impact make it easy to use for antivirus newbies, and more experienced users will like its feature set.

You should use Avast Free Antivirus if you have other Avast products, such as the excellent Android app, and want a unified antivirus experience. Or, if you like to tinker with PC settings, you may like Avast's unique set of extra tools.

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  • The avast antivirus is ok but now more than that...
    i installed it on my computer and i use to scan my directories every weak, the scan shows nothing but still i sometimes get notification which say i have viruses on my computer.
  • I tried Avast for quite sometime. But got tired of the nagging popups asking to upgrade. I uninstalled and went with Panda Free Antivirus 15.10. So far so good. An occasional popup to let me know an upgrade is available. But does its job silently in the background. I see two files in quarantine.