What the best antivirus software has
- A near-perfect detection rate. Since the role of antivirus software is to detect threats, it should do so flawlessly. Look for certification from a respected, third party testing organization.
- An intuitive interface. Because antivirus software can be customized, it's important that the interface guides users through the various settings.
- Freedom from false positives. The best antivirus software does a good job of detecting malware without being tripped up by legitimate programs. Some software has selectable profiles that adjust the detection levels based on activities, something that's especially important to gamers (who won't want to be bothered with popups or beeps in mid-game).
- Good zero-day performance. Spotting a virus that's widespread is a fairly easy task for most security software. It's harder, however, to squash a bug that's just been released in the wild. Top antivirus software products monitor files and processes, identifying brand-new viruses by spotting activity that is virus-like, and without tripping excessive false alarms (see above).
- Daily updates. Virus signatures are specific strings of binary code that can be detected by antivirus software. Most programs will automatically check for updates on a daily or even an hourly basis. Some free software relies on a manual check.
- A light touch that won't slow you down. While any antivirus program will use some of your computer's resources, a good antivirus program should keep your system free of malware without significantly slowing down your system's performance. In testing, the best antivirus software exacts almost no drag on performance.
Know before you go
Antivirus alone or security suite? Antivirus software comes as a stand-alone program, but you can also purchase it as part of a comprehensive security suite. Security suites, covered in our separate report on Internet security software, are more expensive, but they include a range of protections, including antivirus, anti-spyware and anti-spam programs, identity-theft protection, firewalls and parental controls. If you opt for an antivirus program that doesn't include these features, experts recommend supplementing it with other components, especially a firewall and anti-spyware software.
Check the system requirements. Make sure the antivirus program you choose will work with your Windows or Mac operating system. If you have an older computer, a large antivirus software program can consume a huge percentage of your computing power and you may run into compatibility problems.
Avoid conflicts. Antivirus software rarely plays nicely with similar products from different vendors. Before installing software from another company, completely uninstall any pre-existing security software. That holds true for the antivirus software provided as part of Windows; Microsoft recommends that you uninstall Windows Defender (Windows 8 or later) or Microsoft Security Essentials (Windows 7 or earlier) before installing any third-party antivirus program.
Mac owners: Find out what's covered. Many antivirus programs don't provide as many protections and features for Mac users. Some multi-device software suites have limitations for Apple products but are upgrading their features constantly. Mac users should be vigilant about understanding what they're getting before they pay; discuss the issue with customer service if the information on the company's websites is unclear. This is particularly true of multi-device software suites.
How many licenses do you need? Antivirus software is sold in versions that cover a single product, or up to 10 or more. Multi-computer licenses are generally cheaper on a per-device basis, but that isn't always true, so be careful not to overbuy. Prices vary widely, so shop around.
Paid antivirus software is a recurring expense. Most paid antivirus programs provide updates only for one year, so be prepared to pay annual renewal fees.
Expect limited support with free software. Although some antivirus programs come with free telephone support, it is rare to find this feature with free software. Even online or chat support isn't guaranteed with free products.
With paid antivirus software, start with a free trial. AV-Comparatives.org recommends downloading a free trial of your chosen antivirus software to ensure you like how it works. Most companies offer at least a 30-day free trial.