You do not need to pay for antivirus on Windows. The best free antivirus options for Windows now score at or near the top of independent lab tests, and Windows 11 and Windows 10 already include one. The real question is whether a third-party free antivirus adds enough to replace the built-in protection.
Quick verdict: for most people, Microsoft Defender is the best free antivirus because it is already installed, has no upsells and scores well in lab tests. If you want a third-party option, Avast Free Antivirus and Bitdefender Antivirus Free are the strongest picks, and AVG and Avira are solid alternatives.
Quick picks
| Antivirus | Best for | Price | Recent AV-TEST result (out of 18) |
|---|---|---|---|
| Microsoft Defender | Most people | Free, built in | 17.5 (July–August 2026) |
| Avast Free Antivirus | Best third-party free pick | Free | 18 (July–August 2026) |
| Bitdefender Antivirus Free | Simple, focused protection | Free | Not tested often; shares engine with paid Bitdefender |
| AVG AntiVirus Free | Lightweight option | Free | 18 (July–August 2026) |
| Avira Free Security | Bonus tools and cross-platform | Free | Free version not lab-tested; Avira Internet Security (paid) scored 18 (July–August 2026) |
Lab scores change from one test round to the next, and different reviewers report slightly different numbers for the same product. Check av-test.org for the latest cycle before you decide.
The best free antivirus for Windows, compared
Our picks are based on independent lab results (AV-TEST, AV-Comparatives) and the sources listed below; we did not run our own lab tests.
1. Microsoft Defender: best for most people
Defender is built into Windows 10 and 11, runs quietly, shows no ads and needs no setup. It scored 17.5 out of 18 in AV-TEST’s July–August 2026 home-user test, with full marks for protection and half a point lost on performance. AV-Comparatives recorded 99.93% online protection with 3 false alarms in its March 2026 malware test, though offline detection was lower at 89.2%.
Watch out for: a basic interface and fewer extras.
2. Avast Free Antivirus: best third-party free pick
Avast is the strongest free third-party option in recent testing. AV-TEST gave it a perfect 18/18 in its July–August 2026 test. It adds web and email protection and other extras, though some stronger firewall and web-protection controls may be limited to paid editions.
Watch out for: upgrade prompts, and the company’s past privacy case over its Jumpshot data business, which was settled with the FTC in 2024.
3. Bitdefender Antivirus Free: best focused alternative
Bitdefender’s free edition runs on the same engine that earns top marks for its paid suite, with real-time protection, malware scanning and basic ransomware protection, and it is Windows-only. It is a good fit if you want a dedicated antivirus without clutter.
Watch out for: fewer features than the paid suite, and the free edition itself is tested less often by the labs.
4. AVG AntiVirus Free: best lightweight option
AVG shares its engine family with Avast and scored 18 out of 18 in AV-TEST’s July–August 2026 test. It has a simple interface and works on Windows and Mac.
Watch out for: it is owned by the same company as Avast and Avira, and pushes upgrades.
5. Avira Free Security: best for extras
Avira’s free tier includes a software updater and covers Windows, Mac, Android and iOS. AV-TEST tests Avira Internet Security, a paid product, rather than the free version; Avira Internet Security scored 18 out of 18 in the July–August 2026 test.
Watch out for: the free version itself is not lab-tested, and some features are limited on the free plan.
Also mentioned: Malwarebytes Free and Kaspersky Free
Malwarebytes Free is useful for second-opinion scans, but it is not a full replacement for real-time protection. Kaspersky Free is available only outside the US, where the company’s products are banned.
Is Microsoft Defender enough? Free vs paid
For malware detection, mostly yes. Independent tests show the gap between free and paid engines is small at the top. Where paid products still pull ahead is in extras and live web protection.
| Free antivirus | Paid suite | |
|---|---|---|
| Malware detection | Excellent at the top | Excellent |
| Real-time protection | Yes (check each free tier) | Yes |
| Firewall | Windows Firewall, or built in to some free apps | Usually included |
| VPN, password manager, backup | Limited or trial only | Often bundled |
| Ransomware rollback and extra layers | Basic | Stronger |
| Anti-phishing in the browser | Varies | Often stronger |
| Cost | $0 | Paid, with higher renewal prices |
Paid products can make sense if you want a bundled VPN and identity tools, or cover for several devices. For one Windows PC and careful habits, Defender or one of the free options above is enough.
Do not run two real-time antivirus programs at once. They can conflict and slow down your PC. Installing a third-party antivirus normally switches Defender’s real-time scanning off automatically.
How to choose and stay safe
- Start with what you have. Open Windows Security and confirm Defender’s real-time protection is on.
- Add a third-party app only if you want its extras, such as a firewall, a safer-browsing add-on or cross-platform cover.
- Check the free plan. Make sure it includes real-time protection, because some free tiers only scan on demand.
- Watch for bundled offers. Decline extra toolbars, cleaners and trials during install.
- Keep Windows and apps updated. Updates close the holes malware uses.
- Use a second-opinion scanner occasionally. A tool like Malwarebytes Free can scan on demand without replacing your main antivirus.
- Practice safe habits. Do not open unexpected attachments, avoid cracked software, use strong unique passwords and keep backups. Habits matter more than which free product you pick.
FAQ
What is the best free antivirus for Windows 11? Microsoft Defender for most people, since it is built in and scores near the top in lab tests. Avast Free Antivirus is the strongest third-party alternative.
Is Windows Defender enough? For a typical home user, yes. It earned a top AV-TEST score in 2026 and protects against most malware without extra software.
What is the best free antivirus for Windows 10? The same picks apply: Defender, Avast Free, Bitdefender Free and AVG. Windows 10 reached end of support on 14 October 2025. Home users can still get security updates until 12 October 2027 through Microsoft’s Extended Security Updates program, free if you sync your PC settings, but upgrading to Windows 11 is the long-term fix.
Is free antivirus safe? Reputable ones are. Avoid unknown tools from pop-ups, and note that some free products collect data, so read the privacy policy.
Can I run two antivirus programs? Not at the same time. Use one real-time antivirus, plus an on-demand scanner if you want a second opinion.
Is Kaspersky Free available in the US? No. It is banned in the US, though it may be available in other countries.
Sources
- Antivirus Review: Microsoft Defender review (AV-TEST and AV-Comparatives 2026)
- Antivirus Review: Free vs paid antivirus
- Antivirus Review: Best free antivirus software
- iTechGuides: Best free antivirus (updated August 2026)
- Tech Insider: Best free antivirus 2026
- AV-TEST: Best Windows antivirus for home users
- Microsoft: Windows 10 Extended Security Updates
Checked 8 November 2026. Lab scores change every test round, so check av-test.org and av-comparatives.org for the latest.
About the Author
Aman Ullah Hridoy
Founder & Content Creator
I’m Aman Ullah Hridoy, the founder of Technolozia. I write about technology, software, gadgets and practical how-to guides to help readers understand tech and make smarter digital choices.
