Avast Free Antivirus can scan your PC for viruses and malware in five different ways, and it isn’t always obvious which one to use or where to find it.
In this guide I’ll show you how to run every Avast scan, step by step: Smart Scan, Targeted Scan, the right-click Explorer Scan, Full Virus Scan and the Boot-Time Scan. I’ll also show you how to schedule a scan, what to do when Avast finds something, and where to find Avast Quarantine.
These steps are for the current version of Avast Free Antivirus on Windows 11 and Windows 10. Avast has moved things around in the last couple of years, so if you remember the Scan Centre or the Deep Scan, I’ll show you where they’ve gone.
The Short Version
- Open Avast and click Run Smart Scan for a quick check.
- For a full check, click Protection, then Virus Scans, then Full Virus Scan.
- If you think your PC is infected, run a Boot-Time Scan first, then a Full Virus Scan.
- Anything Avast finds goes into Quarantine (Protection, then Quarantine), where it can’t do any harm.
Avast Antivirus Scans Available
Avast Free Antivirus has five types of virus scan. Smart Scan has its own big button on the main screen. The others are under Protection (in the left hand panel), then Virus Scans, apart from the Explorer Scan, which is on the right-click menu.
- Smart Scan: the everyday quick scan. It checks for viruses and malware, browser threats, outdated apps and other problems, and usually only takes a few minutes.
- Full Virus Scan: Avast’s in-depth scan of your whole PC, including the hard drives, rootkits (malware that hides itself) and programs that start with Windows. This used to be called the Deep Scan.
- Targeted Scan: checks only the folders or drives you choose, such as your Downloads folder or a USB stick.
- Explorer Scan: checks a file or folder straight from the right-click menu in File Explorer.
- Boot-Time Scan: runs as your PC starts, before Windows loads, so it can catch malware that hides once Windows is running.
Where Has the Avast Scan Centre Gone?
Older versions of Avast had an Explore button and a Scan Centre, with a scan called Deep Scan.
In the current version, the scans are under Protection, then Virus Scans, and the Deep Scan is now called the Full Virus Scan. It does the same job.
Which Avast Scan Should You Run?
Here’s the simple version of which scan to use and when.
- A quick weekly check: Smart Scan. Better still, schedule it so it runs by itself.
- You’ve downloaded a file and aren’t sure about it: right-click it and use the Explorer Scan.
- Someone has given you a USB stick: Targeted Scan, before you open anything on it.
- A thorough check once a month: Full Virus Scan.
- You think your PC is infected: Boot-Time Scan first, then a Full Virus Scan once Windows has restarted.
How to Run a Smart Scan
The Smart Scan is the quickest and most used Avast virus scan. It’s the one Avast asks you to run as soon as it’s installed.
- Open Avast Free Antivirus from the Start menu or the desktop.
- On the Status screen, click Run Smart Scan.
You can also start it from Protection, then Virus Scans.
Avast Smart Scan
So what is the Avast Smart Scan? It’s a quick all-in-one check. Rather than reading every file on your PC, it checks the places malware usually hides, plus a few other things that can leave you open to attack.
- Viruses and other malware
- Browser threats, such as dodgy add-ons and search engines you didn’t choose
- Outdated apps that need security updates
- Network and performance problems
It doesn’t usually take long, but exactly how long depends on your PC.
If the scan finds anything, click Resolve all. If you need to stop the scan for any reason, click Stop scan.
What Do Avast Advanced Issues Mean?
Avast will probably then tell you about advanced issues. These may or may not matter, but the main thing to know is that you need the paid version, Avast Premium Security, to fix them.
If you want to stay with the free version, click Skip for now.
Don’t Skip Real Threats
If the Smart Scan finds an actual virus or other malware, always click Resolve all. That’s free, and it’s the whole point of the scan.
It’s only the advanced issues that need the paid version. These “issues” aren’t actual malware, they’re possible security flaws that the Premium version will close. And quite honestly, it’s there to frighten you in to buying.
How to Schedule an Avast Smart Scan
At the end of the scan, Avast gives you the option to schedule a Smart Scan. I’d turn this on, so Avast checks your PC regularly without you having to remember. Then click Close smart scan.
To change when it runs, click Edit frequency on that same screen. Or, at any time:
- Click ☰ Menu, then Settings.
- Click Protection, then Smart Scan.
- Under Automated Smart Scan scheduling, pick the frequency, the day and the start time.
Quick Tip
Pick a time when your PC is usually switched on but you’re not busy on it, like lunchtime. If the PC is off at the scheduled time, the scan won’t run then.
The Targeted Scan
The Targeted Scan checks just the folders or drives you choose, and nothing else. It’s ideal for your Downloads folder, or for a USB stick someone has given you.
- Open Avast and click Protection, then Virus Scans.
- Click Targeted Scan.
- Pick the folder or drive you want to check and start the scan.
Not sure where your downloads end up? Here’s how to find your browser’s download folder.
Scan a File or Folder from the Right-Click Menu
The quickest way to check a single file or folder is the Explorer Scan, which runs straight from the right-click menu in File Explorer.
- Right-click the file or folder you want to check.
- On Windows 11, click Show more options first.
- Click Scan selected items for viruses.
Windows 11 Right-Click Menu
Windows 11 uses a much shorter right-click menu than earlier versions of Windows, which is why you have to click Show more options first.
If you’d rather have the full menu every time, here’s how to restore the old right-click menu in Windows 11.
Run a Deep Scan with Avast Antivirus (Now Called Full Virus Scan)
The Full Virus Scan is Avast’s full system scan. It checks every file and folder on your PC for signs of malware, along with rootkits and the programs that start with Windows. In older versions of Avast this was called the Deep Scan.
If the Smart Scan found anything suspicious, that’s the time to run a full scan.
- Open Avast and click Protection, then Virus Scans.
- Click Full Virus Scan.
Running a Full System Scan with Avast Free Antivirus
Avast starts scanning and shows you its progress. Because a full scan can take a long time, you can tick Shut down computer after scan finishes. Handy if you start it before bed.
How Long Does an Avast Full Scan Take?
Anything from 30 minutes to a few hours. It depends on how fast your PC is, whether it has an older hard drive or a faster SSD, and how many files you have.
Close any other programs while it runs, and make sure the PC won’t go to sleep halfway through. Here’s how to stop your computer going to sleep.
If yours seems to take forever, I’ve covered the reasons in why your antivirus takes so long to scan.
If the Scan Found Something
If the Full Virus Scan finds something, Avast lists the files for you.
- Check which files Avast is flagging. Most of the time I’d just remove them all, but it’s worth a quick look first. Click Select all.
- Click Resolve all.
- When all the threats are secured, click Done.
Why Check Before You Resolve?
Every antivirus program gets it wrong now and then, and flags a safe file as a threat. This is called a false positive.
Resolving a threat usually moves it into Quarantine, so you can still get it back if it turns out to be safe.
Running a Boot Time Scan with Avast
The Avast Boot-Time Scan runs before Windows loads. Some malware hides itself once Windows is running, so scanning before Windows starts gives Avast a better chance of finding and removing it.
Because it runs before Windows, you set it up now and it runs the next time you restart your PC.
The boot time scan is one of the most powerful functions of Avast and if you do suspect any sort of infection, then this is well worth using.
Choose What Avast Does with Threats First
Out of the box, the Boot-Time Scan is set to manual mode. That means if it finds something, it stops and waits for you to decide what to do, on a plain screen before Windows has loaded.
I’d change this before you start, so the scan can deal with threats by itself:
- Click Protection, then Virus Scans.
- Click the Settings gear icon on the right.
- Click the Boot-Time Scan tab.
- Under Automatic actions during scans, choose Fix automatically (recommended).
- Then click the X Close option in the left hand corner.
Schedule a Boot Time Virus Scan
To run a boot time scan, Avast needs to download a separate list of virus definitions to use.
- Click Prepare scan. Avast gets the scan ready, which can take a minute.
- Close any open programs, then click Restart now.
What Happens When Your PC Restarts
As your PC restarts, instead of the normal Windows start-up, you’ll see the Avast Boot-Time Scan running on a plain screen.
- You can cancel the scan at any time by pressing the Esc (Escape) key on your keyboard.
- Avast lists any files it identifies as malware, with the progress as a percentage underneath.
- When the scan finishes, Avast briefly shows the results and Windows carries on starting up.
Avast says a Boot-Time Scan usually takes several minutes, but on a big, full drive it can take a lot longer.
Moved to Quarantine
If Avast found anything during the Boot-Time Scan, you’ll see a pop-up once Windows has started. Click See results.
That opens the Scan history page, where you can check which files have been moved into Quarantine. Click Done to finish.
Where to Find the Avast Boot Scan Log
Avast saves a text report of every Boot-Time Scan. It’s in a hidden folder, so the easiest way to get there is to copy this line, paste it into the address bar at the top of File Explorer and press Enter:
C:\ProgramData\Avast Software\Avast\reportOpen the file called aswboot.txt to see everything the Boot-Time Scan checked and found.
Where to Find Avast Quarantine
Whatever scan you use, anything Avast removes ends up in Avast Quarantine. Older versions of Avast called this the Virus Chest.
Quarantine is a safe, locked area inside Avast. Whatever is in there can’t run or spread, so it’s fine to just leave it. Here’s how to find it:
- Open Avast.
- Click Protection, then Quarantine.
Or right-click the Avast icon in the notification area of the taskbar, next to the clock, and click Open Quarantine.
How to Restore a File from Avast Quarantine
Only do this if you’re sure the file is safe, for example a program you’ve used for years that Avast has suddenly flagged.
- Tick the box next to the file.
- Click the … (More options) button.
- Click Restore to put it back where it was, or Restore and add exception if you want Avast to stop flagging it.
To get rid of a file for good, tick it and click Delete. This can’t be undone.
If you’re not sure whether a file is safe, leave it in Quarantine. It can’t do any harm there.
Is Avast Free Good Enough?
For protection, yes. In the latest independent tests from AV-TEST (August 2026), Avast Free Antivirus scored full marks for protection, performance and usability, and won a Top Product award.
There are two catches. The first is the adverts. As you’ve seen, Avast regularly nudges you towards its paid products, and none of them are needed to keep you safe from viruses.
The second is privacy. In 2024 the US Federal Trade Commission ordered Avast to pay $16.5 million for selling people’s web browsing data through its Jumpshot company, and banned it from selling browsing data for advertising. It’s worth knowing about before you decide.
Avast or Windows Security: Which Should You Use?
Windows 11 and Windows 10 already have their own antivirus, Microsoft Defender, which lives in the Windows Security app. It also won a Top Product award in the same round of AV-TEST tests, and it has no upgrade pop-ups.
When you install Avast, Windows switches Microsoft Defender off automatically, so the two don’t clash. If you ever uninstall Avast, check that Windows Security has switched back on.
My advice: if you’re happy with Avast, keep it. If the pop-ups confuse you, or the privacy history puts you off, Windows Security does the job just as well. Here’s how to use Windows Security.
Only Run One Antivirus
Never install two antivirus programs at the same time. They fight over the same files and slow your PC down. That includes Avast and AVG, which come from the same company.
A one-off second opinion scanner like Malwarebytes Free is the exception, and I’ll come back to that below.
Troubleshooting Avast Scans
The Smart Scan Is Slow or Stuck
A Smart Scan normally takes a few minutes. If it hasn’t moved for ten minutes or more, click Stop scan, restart your PC and try again.
I’ve covered the common causes of slow scans in my guide to slow virus scans.
The Boot-Time Scan Is Taking Forever
The Boot-Time Scan checks your drives before Windows starts, so on a big, full drive it can take an hour or more. That’s normal. If you need your PC back, press Esc to skip it.
If it keeps stopping halfway through, it’s probably waiting for you to choose what to do with a threat. Set it to Fix automatically, as shown above.
Avast Won’t Open or Won’t Update
First, restart your PC. If that doesn’t help, update Avast by hand:
- Right-click the Avast icon in the notification area of the taskbar.
- Click Update, then Engine and virus definitions.
- If it doesn’t start checking by itself, click Check for updates.
- Do the same again with Update, then Program.
Still not working? Repair Avast. This keeps your settings:
- Right-click the Start button and click Installed apps (on Windows 10 it’s Apps and Features).
- Find Avast Free Antivirus, click the three dots next to it and click Uninstall, then Uninstall again.
- If Windows asks for permission, click Yes.
- In the Avast Setup window, click Repair, then Yes.
- When it’s finished, click Restart computer or Done.
Don’t worry about clicking Uninstall. It only opens the Avast Setup window, and nothing is removed unless you choose to in there.
Avast Keeps Finding the Same Threat
If Avast finds the same malware every time you scan, something is putting it back. Run a Boot-Time Scan, then a Full Virus Scan, then get a second opinion with Malwarebytes Free. Here’s how to scan for malware your antivirus missed.
Can’t Open Avast at All?
Some malware stops your antivirus from opening. If that happens, you can schedule a Boot-Time Scan from Safe Mode instead.
- Restart your PC in Safe Mode with Command Prompt. If you’re not sure how, here’s how to get into Safe Mode.
- Type these three lines one at a time, pressing Enter after each one.
cd "C:\Program Files\Avast Software\Avast"
sched /A:*
shutdown /rThe first line opens Avast’s folder, the second schedules a scan of all your drives and the third restarts your PC. The Boot-Time Scan then runs before Windows loads.
Avast Scan FAQ
Q: What is Avast Smart Scan?
A: Smart Scan is Avast’s quick all-in-one check. It looks for viruses and malware in the places they usually hide, plus browser threats, outdated apps and network problems. It usually takes a few minutes.
Q: Where has the Avast Deep Scan gone?
A: It’s now called the Full Virus Scan. Open Avast, click Protection, then Virus Scans, then Full Virus Scan. It does the same job as the old Deep Scan.
Q: How long does an Avast scan take?
A: A Smart Scan usually takes a few minutes. A Full Virus Scan can take anything from 30 minutes to a few hours, depending on your PC and how many files you have. A Boot-Time Scan usually takes several minutes, but can take an hour or more on a big, full drive.
Q: Where is the Avast Virus Chest?
A: The Virus Chest is now called Quarantine. Open Avast and click Protection, then Quarantine. You can restore or delete each file from there.
Q: Where is the Avast boot scan log?
A: Avast saves Boot-Time Scan reports in a hidden folder, ProgramData, then Avast Software, then Avast, then report. Open the file called aswboot.txt to see the results.
Q: Is there an Avast online virus scan?
A: No. Avast doesn’t offer a scan that runs in your web browser. Its free virus scanner page tells you to download and install Avast first. Be wary of any website that claims to scan your PC in the browser and then says you’re infected. That’s a common scam.
Q: Is Avast Free Antivirus the same as Avast One?
A: Not quite. Avast One is Avast’s all-in-one app, and its free version includes Avast Free Antivirus. If you download Avast for free from avast.com, you’ll get Avast Free Antivirus, and the scans work the same way.
Q: Can I use Avast and Windows Security at the same time?
A: You don’t need to. When you install Avast, Windows turns off Microsoft Defender automatically so the two don’t clash. Never install two full antivirus programs together. A one-off scanner like Malwarebytes Free is fine as a second opinion.
Q: Is Avast the same as AVG?
A: They’re separate programs, but both are owned by Gen Digital and use the same detection engine. That’s why Avast and AVG look and work in such a similar way. Don’t install both.
Q: Is Avast Free good enough?
A: For protection, yes. In AV-TEST’s August 2026 tests, Avast Free Antivirus scored full marks for protection, performance and usability. The downsides are the regular adverts for Avast’s paid products and its past record on selling browsing data.
Summary
Although it’s free, Avast Free Antivirus comes with some powerful scans, and it protects your PC in the background all the time.
- Schedule a weekly Smart Scan to catch anything you might have picked up by accident.
- Use the right-click Explorer Scan on anything you download before you open it, and a Targeted Scan on any USB stick.
- Run a Full Virus Scan about once a month.
- If you think your PC is infected, run the Boot-Time Scan first, then a Full Virus Scan.
- Anything Avast removes goes into Quarantine, where it’s safe to leave.
Related Guides
How to Scan PC with AVG Free Antivirus
AVG is Avast’s sister program, and it’s free too.
Scan Computer for Malware Your Antivirus Missed
If you suspect you’ve been infected, get a second opinion with Malwarebytes.
How to Use Microsoft Windows Security
Windows’ own antivirus is free, built in and very good.
Beware of Device Encryption on Windows 11 Home
Device Encryption is silently being enabled on all Windows 10 and Windows 11 Home editions that meet the hardware requirements and you’re signed in with a Microsoft account.
It’s very important that you check whether or not device encryption is enabled on your computer and if it is, then you MUST either disable it or find your recovery key. I’ll show you how to do both.
You can find this and other related step by step guides in – At Home Computer Security Guides
Written by Jeff Porter. I’ve been fixing Windows PCs since 2010 and I’m CompTIA Network+ certified. More about me