Is Windows Defender enough? Do Macs need antivirus?

For many people, yes. The protection built into Windows, Macs, iPhones and Android phones is a solid base, as long as you keep your devices updated and stay alert to scams. Independent labs rated Microsoft’s built-in antivirus well in 2026, though not at the top of every test. A paid antivirus is an option, not a requirement.

Windows: what you already have

Antivirus software scans files and websites for malware. Malware is software built to harm your device or steal your data. On Windows, the antivirus is Microsoft Defender Antivirus, the program many people still call Windows Defender. It lives inside the Windows Security app. Microsoft says the app is built into Windows and protects your device from the moment you start it. The app also includes a firewall, which watches the traffic going in and out of your PC. On Windows 11, it includes Smart App Control, which can block apps that Microsoft considers malicious or untrusted. Real-time protection is the setting that scans files as you open or download them. If you switch it off, Microsoft says it turns itself back on soon.

If you install another antivirus program, Windows turns Defender off on its own, according to Microsoft’s documentation. That keeps two programs from fighting each other. Don’t try to run both.

What independent labs found

Two well-known testing labs publish results on home antivirus products: AV-TEST in Germany and AV-Comparatives in Austria. Here is what they found for Defender in 2026.

• AV-TEST, July and August 2026. The lab tested 15 home products on Windows 11. Each product can earn up to 6 points for protection (blocking malware), performance (how much it slows your PC) and usability (false alarms). Defender scored 6, 5.5 and 6. That is 17.5 out of 18, enough for AV-TEST’s “TOP PRODUCT” award, which starts at 17.5 points.
• AV-Comparatives, February to May 2026. The lab ran 400 real-world threats against 20 home products. Defender blocked 396, a 99.0% protection rate. It caused no false alarms and earned the lab’s top award, ADVANCED+, as six other products did.
• AV-Comparatives, September 2026. The lab used 10,000 malware samples. With an internet connection, Defender’s protection rate was 99.89%. With no connection, it detected 82.2% of the samples. It also wrongly flagged 28 clean files, which the lab calls “very many” on its scale. Defender was not among the six products that earned the top award in that test.

AV-Comparatives has described an offline gap like this as a design choice, not a flaw. Defender relies heavily on cloud-based checks. The gap matters most when those checks aren’t available, such as on a restricted network or while traveling.

Read these numbers with care. Each test shows one slice of protection, and AV-Comparatives itself says not to buy a product based on a single test. Both labs also earn money from the security industry in some way. AV-TEST lets its customers use its seals after they pass a test cycle. AV-Comparatives says vendors can pay for consulting and for the right to use its logos, while joining its public tests is free. It also says its site carries no ads or paid referral links.

AV-Comparatives sums it up in a May 26, 2026 commentary. For many home users with straightforward habits, it says, Defender gives “a meaningful baseline of protection straight out of the box.” It adds that tests still show differences between products.

Keep Windows itself updated

Updates matter more than the brand of antivirus. Windows 10 reached the end of support on October 14, 2025. Microsoft says a PC without security updates is at greater risk from viruses and malware. Its consumer Extended Security Updates program can protect a Windows 10 PC until October 12, 2027. If your PC qualifies, Microsoft says the upgrade to Windows 11 is free. You can check under Settings, Windows Update.

Macs: built-in protection

Apple builds malware defenses into macOS in three layers. The App Store, or Gatekeeper together with notarization, tries to stop malware from launching. Gatekeeper, notarization and XProtect block malware from running. XProtect also removes malware that has already run. Gatekeeper is the check that decides whether an app may open. Notarization means Apple scanned an app for known malware before you got it. XProtect is Apple’s built-in antivirus technology, and macOS checks for updates to it daily by default.

Apple presents these layers as its answer to viruses and malware. Its documentation also describes what happens when new malware is found: Apple can revoke an app’s notarization and release new XProtect signatures. For most Mac owners, we think the sensible baseline is these built-in layers plus updates and careful downloads. Apple says the App Store is the safest place to get Mac apps. It also warns that running software that is not signed and notarized can expose your Mac to malware.

iPhone and Android

On an iPhone, Apple says all third-party apps are sandboxed. A sandbox walls each app off. It is designed to stop an app from reading other apps’ data or changing the device. Read more in our guide on whether iPhones can get viruses.

On Android, Google Play Protect is on by default. It checks apps from the Play Store before you download them. It also scans your device for harmful apps from other sources and can warn you or remove them. Google recommends keeping it on. To check, open the Play Store, tap your profile picture, tap Play Protect, then Settings, and look at “Scan apps with Play Protect.”

When an extra tool can make sense

AV-Comparatives says tests still show gaps between products in a few areas. They include protection when you have no internet, phishing protection if you don’t use Microsoft’s own browser and mail apps, and extras such as identity monitoring. So an extra tool may be worth a look if:

1. You often work offline or on restricted networks.
2. You use another browser or mail app and want checks that work across them.
3. You want a feature that Defender doesn’t offer, and you have read what it does.

Judge any product by what it adds, not by fear. This page doesn’t recommend or link to any product.

What can go wrong

One risk that antivirus can’t fix is the fake alert. The FTC says tech support scammers start with a bogus warning, such as a pop-up that looks like it comes from a well-known company and tells you to call a number. They then ask for remote access to your computer and charge a fee to remove a problem that doesn’t exist. The FTC’s two rules: real tech companies don’t contact you to say your computer has a problem, and real security pop-ups never ask you to call a phone number. If you think there is a real problem, the FTC says to update your security software, run a scan, and ask someone you trust for help.

Fake renewal notices are another trick. Scammers send texts or emails saying you were charged hundreds of dollars to renew a tech support subscription, and they use the names of well-known companies. The FTC says to contact the company at a phone number you know is real, not the one in the message. Then check your card or bank account. If there is no such charge, the message was a scam.

Antivirus software can’t stop you from handing over money or a password yourself. For more on spotting scams, see our guide on AI scams. For warning signs on your phone, see how to tell if your phone is hacked.

What to do now

1. On Windows, open the Windows Security app, choose Virus & threat protection, and check that nothing needs your action. Run a Quick scan if something seems wrong.
2. Turn on automatic updates. If you still use Windows 10, check whether your PC can move to Windows 11 or qualifies for Extended Security Updates.
3. On a Mac, install macOS updates and download apps from the App Store or from identified developers.
4. On Android, make sure “Scan apps with Play Protect” is on. On an iPhone, install iOS updates.
5. If a pop-up says your computer is infected and gives a phone number, close it and don’t call. Report it at ReportFraud.ftc.gov.