How to Remove Viruses and Malware from Windows for Free
Sudden pop-ups, programs you never installed, unexplained slowness — most infections can be cleaned without paying a cent, using Windows Defender plus one second-opinion scanner.
If your PC suddenly acts strange — ads that should not appear, programs you never installed, unexplained slowness — you may have a virus or malware. In most cases you do not need to pay anything to fix it.
The plain-language explanation
"Virus" and "malware" are not exactly the same thing: malware is the umbrella term for any malicious program (viruses, spyware, adware, trojans...), whereas a virus is just one specific type that replicates itself. In practice, the removal process is similar for all of them.
Signs you may have malware
- Browser windows or tabs open that you did not open yourself.
- The PC runs much slower than usual, especially at startup.
- Programs are installed that you do not remember adding.
- Your browser's home page or search engine has changed on its own.
- The fan runs at full speed even when you are doing nothing demanding.
Step by step to remove it
1. Disconnect the computer from the internet
This stops the malware from sending data out or downloading more components while you clean it.
2. Run a full scan with Windows Defender
Go to Settings → Privacy & security → Windows Security → Virus & threat protection → Scan options → Full scan. It takes a while, but it is free and built into Windows.
3. Get a second opinion with Malwarebytes
1. Download the free version from malwarebytes.com
2. Install and open the program
3. Click "Scan" (full scan)
4. Quarantine everything it finds
5. Restart the computer
No antivirus catches 100% of threats, so using two different tools greatly increases the odds of finding everything.
4. Review your browser extensions
A lot of adware installs itself as a browser extension. Check Chrome/Edge → Extensions and remove anything you do not recognise.
Tip: after cleaning the machine, change your important passwords (email, banking) from ANOTHER device, in case the malware captured them before you removed it.
Warning: distrust any ad or pop-up claiming "we have detected a virus, call this number" — it is almost always a scam (fake tech support), not a genuine Windows alert.
Common mistakes
Installing several paid antiviruses at once to "be extra safe" usually backfires: they can trigger false positives against each other and slow the machine down more than the malware itself. An up-to-date Windows Defender plus an occasional Malwarebytes scan is enough for most home setups.
Frequently asked questions
Is Windows Defender enough, or do I need to pay for another antivirus?
For most home users with normal browsing habits, an up-to-date Windows Defender provides solid, free protection. A paid antivirus can add an extra layer, but it is not essential.
How do I know the malware is fully removed?
If both a full Windows Defender scan and a Malwarebytes scan come back clean, and the strange behaviour has stopped, that is a good sign. If symptoms persist, a clean reinstall of Windows may be needed.
Can Macs get viruses too?
Yes, although less frequently than Windows. macOS can also be affected by malware, especially adware and malicious apps downloaded outside the App Store.