How to Schedule an Automatic Scan with Windows Defender
Using Task Scheduler, including the condition so it doesn't drain battery on laptops.
Windows Defender already scans your machine in the background during idle moments, but if you want a full scan at a specific time (overnight, for example, so you don't notice the CPU usage), there's no direct option inside the Windows Security app itself — you need to use Task Scheduler.
Note: Windows Defender needs to be active for this task to show up as available. If you don't have another antivirus installed, it should be by default — you can confirm this in our guide on how to know if Windows Defender is really active.
Steps
- Search for "Task Scheduler" on Windows and open it.
- In the left panel: Task Scheduler Library → Microsoft → Windows → Windows Defender.
- Double-click "Windows Defender Scheduled Scan".
- "Triggers" tab → "New".
- "Begin the task": "On a schedule" — choose daily, weekly or monthly, and your preferred time.
- Check "Enabled" and "OK".
Tip: if you use a laptop, also go to the "Conditions" tab and check "Stop if the computer switches to battery power" — that way the scan only runs while plugged in, avoiding unexpected battery drain.
How often is it worth scheduling it?
Once a week is a reasonable starting point for a full scan — Windows Defender already covers day-to-day protection with its real-time protection and quick background scans, so a daily full scan isn't needed for most home use.
If the scan uses too much when running
You can combine this schedule with a CPU limit, so it doesn't affect other tasks too much even during its scheduled time — we explain this in how to optimise Windows Defender's resource usage.
Frequently asked questions
Why doesn't the Windows Defender task show up in Task Scheduler?
The most common cause is that Windows Defender isn't active at that moment (for example, if you have another antivirus installed). Confirm it's active before looking for the task.
Do I need to leave the computer on at the scheduled time?
If you check the 'Wake the computer to run this task' option under conditions, Windows can wake the machine from sleep, run the scan, and put it back to sleep afterwards.
Can I schedule a quick scan instead of a full one?
Yes, though the quick scan already runs more frequently automatically by default — scheduling manually usually makes more sense for the full scan, which Windows doesn't do as often on its own.