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Looking for the best free antivirus software? You've come to the right place. Find out which program meets your needs by using the results of our in-depth antivirus lab tests. 
To find the very best antivirus software for your PC, we bombard free and paid-for antivirus software with tens of thousands of threats in our tests, including viruses, ransomware and phishing attacks designed to compromise and steal data. We repeat this four times a year, as new threats are emerging all the time. This means that you can be confident that any program we say is the best, really is.
Thanks to our test results, we can also save you money. We know that free and paid-for versions of the same software have the same protection. So unless you want extra features or extra piece of mind, opt for one of our best free antivirus programs. 
Do you use a Mac? See our expert pick of the Best antivirus for Macs 
You can save yourself over £100 a year by choosing a good free antivirus program. But be careful – we've found that some free options are annoying to use, have irritating pop-ups and quite simply aren't as good as rivals when it comes to protecting your devices. So you need to make sure that the software you install is one of the best programs, which you can do by using the results of our tough, independent lab tests. 
Which? members can log in to see the full results. Not yet a member? Join Which? to unlock our antivirus results, along with all of our online reviews, including laptops, tablets and mobile phones.
We recommend you install one of our recommended best free antivirus programs if you want to save money, as they can perform just as well as ones you can pay for. However, what you're more likely to get with paid-for software are extra features, such as multiple licences, and you won't have to put up with annoying ads. 
So if this appeals to you, make sure your antivirus software is worth your money by picking one of the best paid-for programs from our independent lab tests.
Which? members can log in to see the full results. Not yet a member? Join Which? to unlock our antivirus results, along with all of our online reviews, including laptops, tablets and mobile phones.
Windows is by far the most threatened operating system (OS), due to its dominance in the market – it was the target of more than 80% of all malware in 2020 and 2021 (the latest years we can find data on). So if you have Windows, it may be prudent to look for a more extensive package that covers as wide a range of threats as possible.
Avast is one of the best-known antivirus companies that offers a free edition of its software. It might be light on features, but as long as it gets the basics of security and anti-phishing right, it could prove to be an excellent choice. We’ve put it through its paces, along with Avast’s paid-for options.
You’ll find Norton pre-installed on lots of laptops and it’s a popular choice in high street retailers. It can be very expensive when you renew, however, so it will need to put in a strong showing to prove it’s worth the cash.
Kaspersky offers both paid-for and free software, and we’ve tested them both.
Below, we've arranged all the antivirus software above in alphabetical order, alongside the key features you might expect to find. Use our table to check whatever software you're interested in has the features you need.
If you want to find out more about each feature, scroll on.  
You can jump back to our best free antivirus software or to our best paid-for antivirus software results, or keep reading to find out more about antivirus software.
Based on our lab tests, we know that our Best Buy free antivirus software will handle common threats, such as the various malware you may face online.
The quality of free antivirus and its ability to detect threats is becoming comparable to many paid alternatives. If you can go without additional features and endure some ads, it might be the best choice for you and your bank balance.
So think carefully about your needs and your online activity, and use our test results to choose the safest option. 
If you do decide to pay, then you should get more for your money. In addition to quality software that can accurately identify and stop a wide range of threats, other features are usually part of the package, too, such as a password manager, parental controls or file clean up, among others. This means you're really just paying for extra features that won't necessarily improve your security, but might be handy.
It's important to keep on top of renewal, as a huge spike in cost after the first year has become the industry standard. It's also generally activated by default, so you'll need to manually go into your account settings if you'd like to choose your renewal preference at the end of each year.
Another thing worth knowing is that paid-for antivirus software will often grant you multiple licences, which is the ability to install the software on multiple devices. Some subscriptions will also include different types of devices, such as Android devices, iPhones and Macs, which may make some antivirus software a better and or more convenient choice for multi-device households. This also allows for the freedom to use parental controls over multiple devices with various operating systems.
If being able to install the software on multiple devices is the only reason you're considering paying, try using the free software on each separate device with a different email address. Alternatively, look into Bitdefender Antivirus Free Edition (Bitdefender Antivirus Free for Windows) – it's free and offers three licences. 
See our expert pick of the best free antivirus software and the best paid-for antivirus software.
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Windows Defender comes preinstalled with Windows 10 and 11, and, for the most part, provides good overall security coverage. Plus, Windows Defender is entirely free of ads unlike free antivirus software, which is largely plagued throughout.
Our lab tests have revealed year-on-year improvements in the effectiveness of Windows Defender, although this was only marginal. 
Once you've activated Windows Defender, it can be set to auto-update for convenience and will automatically upload the latest version when you do an overall update of your operating system. 
Windows Defender has several basic protections that are suitable for everyday browsing. Its limitations lie in areas such as scanning. Based on our tests, it can take multiple scans before it detects (and then acts upon) malware.
Oddly, Defender can also be a bit overzealous at blocking items, even those that are safe.
Overall, though, Windows' built-in security is pretty effective. But ultimately, if you're looking for more in-depth, dedicated security online, antivirus software will be a necessary upgrade. If you don't want to pay, then choose from our pick of the best free antivirus software.
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In 2017, the National Cyber Security Council (NCSC), an arm of intelligence agency GCHQ, recommended government departments to not use Kaspersky due to Russia‘s history of attempting to hack critical UK infrastructure. 
The NCSC published further advice in March 2022. The key thing for UK consumers using Kaspersky software to know is unless they're doing work that could be seen as being counter to the interest of the Russian state, the NCSC says it’s highly unlikely they will be targeted directly. 
However, the NCSC did warn that: ‘You may need to move to a new AV [antivirus] product if Kaspersky itself becomes subject to sanctions, since the AV product would likely stop getting updates.'
You can find out more on the NCSC website.
Kaspersky's antivirus didn't rate highly enough in our lab tests to be a Best Buy. Last year it did, but we withheld the award as we decided it wouldn't be right to unequivocally recommend Kaspersky software in light of the war in Ukraine, and worsening relations between Russia and the West.
We aren't currently recommending that Kaspersky customers stop buying its products or using its software. But our tests show there are better packages out there this year, so look to our Best Buys – either our best free antivirus software or our best paid-for antivirus software results.
Our test involves subjecting every piece of software to tens of thousands of threats, including viruses, ransomware and phishing attacks designed to compromise and steal data. We repeat the test four times each year and the scores we publish are based on a full year of testing, giving you confidence that our recommendations have performed consistently. 
For more, see our guide on how we test antivirus software. 
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