Which Free AntiVirus Software is Best?
Ask Bob Rankin
Posted by Bob Rankin on May 23, 2011

"I'm convinced that paying for anti-virus is a waste, so I've decided to dump Norton and go with a free program. I can't decide whether to go with Avast or AVG, since I have friends that swear by both of them. Is there any hard data on which is better at protecting against viruses?"

Comparing AVG, Avast, and Avira

I agree that for most users, one of the free anti-virus programs will perform just as well as Norton, McAfee or other commercial software. But which free anti-virus should you choose?

Avast! Free Antivirus <http://www.avast.com/free-antivirus-download> and AVG Free <http://free.avg.com/us-en/download-avg-anti-virus-free> are two of the most popular free antivirus programs of all time. Over a million copies of each are downloaded in a typical week. Another very worthy contender that you didn't mention is Avira <http://www.avira.com/free>. So let's compare all three, and see which program gives the better overall protection against various forms of malware.

AV-Comparatives.org is an independent antivirus testing service that answers exactly this type of question. Its February, 2011, report says that Avast! detected more than 98 percent of all sample malware thrown at it, Avira found 97.5 percent, while AVG detected only 91.4 percent. The difference held steady between subcategories, with Avast! and Avira outperforming AVG on backdoors/bots (98.5, 99.0, and 92.6 percent respectively), and Trojans (98.4, 97.7, 91.4 percent). AVG and Avira showed larger weaknesses in the malware/virus category, which scored the two at 80.7 and 87.7 percent, compared to Avast's score of 96.7 percent.

False positives - legitimate programs that are erroneously tagged as malware - is a third important criterion for effectiveness. False positives are more than just alarming. They can prevent a necessary program from functioning properly. All anti-malware programs produce false positives occasionally but the fewer, the better. In AV-Compartives' test on a standard set of applications, 19 false positives were reported Avast! and 15 by AVG. Avira reported just 9 false positives.

Other Factors to Consider

Impact on system performance is important when running an antimalware program constantly (as you should). AV-Comparatives tested this impact on a number of computer functions such as file copying, archiving/unarchiving, encoding/transcoding, installing/uninstalling applications, launching applications, and downloading files. Avast, AVG and Avira were all rated "very fast" in most cases, meaning they had less than a 10 percent impact on overall system performance. AVG slowed the installation/uninstallation of programs slightly more than Avast and Avira did, but was still rated as "fast". When downloading files from the Internet, Avast and AVG scored "very fast" and Avira slipped to "fast".

None of the popular free anti-virus programs, Avast, AVG, and Avira, are perfect, as you can see from the test results above. But all three programs do some parts of their jobs better than other anti-malware programs tested. It's worthwhile to take a look at the reports on AV-Comparatives.org <http://av-comparatives.org/> to see how other programs such as BitDefender, ESET, F-Secure, Kaspersky, McAfee, Microsoft and Symantec/Norton stack up in the various testing categories.

It's tempting to jump to the end of the "On-Demand Detection" report and make a decision based on the award levels shown there. But if you poke around further, you'll see that each report (detection, false alarm, performance and removal) has its own award levels, and the players tend to bounce around from one round of testing to another, just months apart. My reading of the data says that both Avast and Avira are rock solid "A+" performers over the long haul, but I'd give AVG an "A" or "A-" grade.

I've used all three on various computers in my home, and it's significant that none of my machines has ever been compromised. Especially when you consider that I scour the Internet for a living, and have kids in the house. Which one is right for you also depends on the types of malware you encounter, the type of websites you visit, and personal preferences as to user interface. 

Copyright 2005 - 2011 - Bob Rankin