The best free antivirus for Windows in 2026 mainly depends on your PC and your tolerance for commercial features. Avast Free and AVG Free achieve the best overall results in the available tests, while Microsoft Defender is sufficient for most everyday use without any additional installation. Bitdefender Free and Avira Free remain interesting, but their free editions are not directly evaluated by all the laboratories.
What is the best free antivirus for Windows in 2026?
Avast Free Antivirus and AVG AntiVirus Free are the choices best supported by independent tests in 2026. Microsoft Defender is the simplest option and already protects Windows 11 directly. Bitdefender Antivirus Free favors straightforward protection, while Avira Free adds several tools whose features remain limited.
An antivirus is software that detects, blocks, and removes malicious programs, including viruses, spyware, and ransomware. Ransomware encrypts files and then demands payment in an attempt to restore them. To better understand the threats covered, our overview of the main types of malware provides a useful foundation.
In August 2026, AV-TEST awarded 18 out of 18 points to Avast Free Antivirus 26.6 and AVG AntiVirus Free 26.6/26.7. Microsoft Defender 4.18 scored 17.5 out of 18: 6/6 for protection, 5.5/6 for performance, and 6/6 for usability.
The endurance test published by AV-TEST on October 21, 2026 confirms the trend over the March to August 2026 period. Avast and AVG finished with 18/18, compared with 17.7 to 17.8 for Microsoft according to the evaluations, with 6/6 in protection for the latter.
| Antivirus | Free protection | Relevant independent result | Main boundary | Recommended profile |
|---|---|---|---|---|
| Microsoft Defender | Real-time protection, ransomware, firewall, SmartScreen | 17.5/18 at AV-TEST in August 2026 | Slightly higher system impact in some tests | User looking for simplicity |
| Avast Free | Files, behavior, and web browsing | 18/18 at AV-TEST in August 2026 | Some advanced features are paid | Older PC or need for stronger web protection |
| AVG Free | Real-time protection | 18/18 at AV-TEST in August 2026 | Restrictions on Windows 11 ARM | Close alternative to Avast |
| Bitdefender Free | Malware and basic protection against ransomware | No direct comparison of the free product in the tests cited in 2026 | Privacy and advanced analysis features are missing | User who wants few settings |
| Avira Free | Moteur d’analyse et détection dans le cloud | The tests cited in 2026 refer to the paid Avira Internet Security | Advanced web protection reserved for the paid plan | User interested in extra tools |
Is Microsoft Defender enough to protect a Windows 11 PC?
Microsoft Defender is generally enough for an up-to-date Windows 11 PC used with legitimate software and regular backups. Included at no additional cost in 2026, Microsoft Defender provides real-time protection and integrates with Windows Security, the firewall, SmartScreen, and tamper protection.
SmartScreen is a reputation filter: it warns when a file, website, or app appears dangerous. Windows Security also offers controlled folder access, an optional feature designed to prevent unauthorized apps from modifying sensitive files.
Microsoft Defender blocked 396 attacks out of 400, or 99.0%, in the real-world test conducted by AV-Comparatives between February and May 2026. Avast and AVG blocked 397, or 99.3%. A gap of 0.3 points does not make Defender a bad choice.
Le compromis concerne plutôt les performances. En avril 2026, AV-Comparatives a mesuré un score d’impact total de 12,9 pour Microsoft Defender, contre 5,5 pour Avast et AVG ; un score inférieur était meilleur dans ce protocole. Le PC de test utilisait Windows 11, un processeur Intel Core i3, 8 Go de mémoire vive et un SSD.
On the projects we work on, we often see systems that are well protected by antivirus software but weakened by outdated software or the lack of backups. Antivirus software does not replace updates or other useful tools for securing a PC.
Avast Free or AVG Free: which should you choose?
Avast Free Antivirus and AVG AntiVirus Free offer nearly identical levels of protection in the independent tests from 2026. Both products blocked 99.3% of the 400 cases in AV-Comparatives and scored 18/18 at AV-TEST in August 2026. The choice therefore depends more on the interface and the features offered.
Avast Free provides shields for files, suspicious behavior, and the web. According to Avast’s 2026 documentation, some firewall capabilities and several advanced protections still require a paid subscription.
AVG AntiVirus Free requires at least 1 GB of RAM and 2 GB of disk space in 2026, according to AVG. On Windows 11 devices equipped with an ARM processor, boot-time scanning and rescue disk are not available.
Close results are not surprising, but they do not guarantee the same experience. Test only one product at a time and check startup, opening business applications, and notifications for a few days. Honestly, gaining a few tenths in a laboratory is not worth an interface that disrupts your teams.
Are Bitdefender Free and Avira Free just as effective?
Bitdefender Antivirus Free and Avira Free offer credible always-on protection, but public 2026 data does not allow them to be directly compared with Avast Free, AVG Free, and Microsoft Defender. The AV-TEST and AV-Comparatives results cited for Bitdefender and Avira generally focus on their paid editions, which are more comprehensive.
Bitdefender Antivirus Free protects Windows in real time against malware and provides basic protection against ransomware. According to Bitdefender in 2026, the offer has no time limit and does not require a credit card. It notably excludes anti-tracking, a full vulnerability scan, and certain usage modes.
The VPN included with Bitdefender Free is limited to 200 MB per device per day in 2026. Avira Free’s is advertised at 500 MB per month. These allowances are for occasional use, not daily remote work, video conferencing, or streaming; our comparison between free VPN and paid VPN explains this trade-off.
Avira states in 2026 that its free offering uses the same core scanning engine and the same cloud detection system as its paid product. The paid edition, however, adds additional scans and advanced web protection. The free add-on tools, such as the password manager or PC cleaner, also have limitations.
How do you choose a free antivirus without slowing down your business?
Choosing a free antivirus should take into account measured protection, impact on endpoints, notifications, and compatibility with business software. For a small business, a free tool may be suitable for a few PCs, but centralized management, support, and incident tracking quickly become more important than the license price.
A free antivirus costs €0 in licensing in 2026, but deploying it takes time. You need to check exclusions, updates, false positives (legitimate files blocked by mistake), and the ability to restore a machine. At this budget level, it is better to keep Microsoft Defender properly configured than to multiply poorly maintained free utilities.
Before changing protection, check these points in order:
- Update Windows 11, browsers, and business software.
- Make sure backups are separate from the PC and that a restore has been tested in 2026.
- Choose a single antivirus that provides real-time monitoring.
- Test the impact on a representative workstation before any company-wide deployment.
- Document alerts, the isolation procedure, and who to notify.
From an agency standpoint, the instinct is to look at the overall risk rather than just the antivirus layer. A protected workstation can still expose data through a reused password, a fraudulent attachment, a permanently enabled administrator account, or a poorly configured remote service.
Can you install two free antivirus programs at the same time?
Two antivirus programs that monitor Windows in real time should generally not run simultaneously. They may scan the same files, increase PC load, and cause conflicts. In 2026, installing a compatible third-party antivirus will normally put Microsoft Defender Antivirus into inactive mode, and Defender reactivates after it is uninstalled.
Seeing Microsoft Defender switch to inactive mode is therefore not necessarily an anomaly. Windows Security may continue to show other security controls, while the third-party product handles the main antivirus scanning.
Les scanners à la demande constituent un cas différent lorsqu’ils n’installent pas une seconde surveillance permanente. Leur usage doit malgré tout rester ponctuel et documenté, particulièrement sur un poste professionnel contenant des données personnelles soumises au RGPD.
Framing endpoint protection in advance avoids redundant installations and blind spots. An outside perspective can especially help connect antivirus, backups, access rights, updates, and incident response into a coherent policy.
FAQ on free antivirus software for Windows
Does a free antivirus protect against ransomware?
A free antivirus can block many ransomware threats, but no protection guarantees a 100% success rate. Microsoft Defender and Bitdefender Free offer protections against this type of threat in 2026; a separate, tested backup remains necessary.
Should you uninstall Microsoft Defender before installing Avast?
Microsoft Defender should generally not be uninstalled before installing Avast Free. According to Microsoft in 2026, Windows automatically puts Defender Antivirus into inactive mode when a compatible third-party antivirus is installed.
Which free antivirus should you choose for an old PC?
Avast Free or AVG Free are worth trying on a low-powered PC, because AV-Comparatives measured a lower impact in April 2026 than Microsoft Defender in its protocol. The real-world result, however, depends on the hardware and software used.
Does Bitdefender Free include unlimited VPN?
Bitdefender Antivirus Free does not include unlimited VPN. In 2026, Bitdefender offers an allocation of 200 MB per device per day, which is insufficient for sustained professional use.
Is a free antivirus suitable for an SME?
A free antivirus may be suitable for a very small organization with few devices and disciplined administration. An SMB with several employees benefits more from centralized management, identified support, and a formal incident-handling process.