Have you ever checked your Windows drive and noticed that a surprisingly large amount of storage is being used by a file called hiberfil.sys? If you’re running low on disk space, you might wonder what this file does, why Windows needs it, and whether deleting it is a good idea.
Here’s the short answer: hiberfil.sys is a legitimate Windows system file that supports hibernation and, on many computers, Fast Startup. It can take up several gigabytes of storage, especially if your computer has plenty of RAM.
Before you make any changes, though, it’s important to understand what hiberfil.sys does and how removing it affects your computer.
Let’s walk through everything step by step.
What Is hiberfil.sys File?
hiberfil.sys is a system file that Windows uses to save information about your computer’s memory during hibernation. It is usually stored in the root directory of your Windows installation drive, typically C:.
You might not see it when browsing your drive because Windows hides protected operating system files by default.
Why Does Windows Create hiberfil.sys?
When your computer is running, its RAM holds information about open applications, documents, and active system processes. RAM is temporary storage, so its contents normally disappear when power is lost.
Hibernation works differently.
When you choose Hibernate, Windows saves the necessary system state to hiberfil.sys and powers down the computer. When you turn it back on, Windows reads that saved information and restores your previous session.
This means you can return to your open applications without relying on the computer to keep using power while you are away.
What Is the Difference Between Hibernate and Sleep?
Sleep and hibernation both help you resume your work, but they operate differently.
Sleep mode keeps your session in memory while using a small amount of power. It is useful when you plan to return to your computer soon.
Hibernate mode saves your session to the storage drive and then powers down. It is particularly useful for laptops when you want to preserve battery life during a longer break.
Hibernation takes longer to resume than sleep in many situations, but it can protect your session if the battery runs out completely.
What Does hiberfil.sys Have to Do With Fast Startup?
Here’s something many Windows users don’t realize: hiberfil.sys can also support Fast Startup.
Fast Startup is a Windows feature that saves certain system information when you shut down your computer. During the next startup, Windows can use that saved information to start more quickly.
Unlike full hibernation, Fast Startup does not save your entire user session. It saves the Windows kernel session and relevant system information.
Because both features rely on hibernation technology, disabling hibernation can also disable Fast Startup.
How Much Space Does hiberfil.sys Use?
The size of hiberfil.sys varies depending on your system configuration, installed RAM, and hibernation settings.
On some computers, it occupies a few gigabytes. On others, particularly systems with more memory, it can use considerably more storage.
The file’s size is not necessarily a sign of a problem. Windows allocates space for the features it supports, and the file can be smaller than your total installed RAM.
If your computer has a 16 GB or 32 GB memory configuration, checking hiberfil.sys is worthwhile when you need additional storage. However, you should decide whether you actually need hibernation before removing it.
What to Do If This File Is Too Big? Should You Delete It?
If hiberfil.sys is taking up too much space, you have three main choices: keep it as it is, reduce its size where supported, or disable hibernation to remove it.
The right choice depends on how you use your computer.
Step 1: Check How Much Space You Have Available
Before changing anything, check your current storage.
Open Settings > System > Storage and review the available space on your Windows drive.
If your drive has plenty of free space, you may not need to change hiberfil.sys at all. If you’re running low on storage, the file could be worth investigating.
Remember that Windows, installed applications, updates, and temporary files also consume disk space.
Step 2: Decide Whether You Need Hibernation
Ask yourself how you usually use your PC.
If you regularly leave many applications open and want to resume your session after shutting down, hibernation may be worth keeping. It can be particularly useful on laptops when battery preservation matters.
If you mainly use Sleep or shut down your computer completely, you may not need hibernation.
Also consider Fast Startup. If you want to keep using that feature, don’t disable hibernation without understanding that Fast Startup may be disabled as well.
Step 3: Open Command Prompt as an Administrator
If you decide to remove hiberfil.sys, use Windows’ power configuration command instead of attempting to delete the file manually.
First, open the Start menu and type cmd into the search box.
Next, right-click Command Prompt and select Run as administrator. Approve the User Account Control prompt if Windows displays it.
You need administrator privileges to change the system’s hibernation configuration.
Step 4: Disable Hibernation
In the administrator Command Prompt window, enter this command:
powercfg.exe /hibernate off
Press Enter.
Windows should disable hibernation and remove hiberfil.sys if the command succeeds. You generally do not need to restart the computer for the change to take effect.
Important: This command also disables Fast Startup on systems that use it. You will no longer be able to select Hibernate until you enable the feature again.
Step 5: Confirm That the File Is Gone
After running the command, return to your Windows drive and check the available storage.
You can open File Explorer, select This PC, and review the free space on your C: drive.
If you want to look for hiberfil.sys directly, remember that Windows hides protected system files by default. You may need to adjust File Explorer’s viewing settings, but you should not change protected-file visibility unless you understand the risks.
The important point is that you should disable hibernation through Windows rather than manually deleting the file.
Step 6: Consider Reducing the File Size Instead
What if you want to keep hibernation but need to recover some storage?
On supported Windows configurations, you can reduce the hibernation file’s size using an elevated Command Prompt.
Enter:
powercfg.exe /hibernate /size 50
Then press Enter.
This requests a hibernation file size of 50 percent of physical memory. Windows may enforce a minimum size, and not every configuration supports the requested size.
Be aware that reducing the file can affect which hibernation options are supported. In particular, a reduced file may not support full hibernation on some systems. Check the command’s result and test your required power options afterward.
If the command fails or you need full hibernation, you can restore the default configuration by entering:
powercfg.exe /hibernate /size 0
This resets the file size to the Windows default behavior rather than disabling hibernation.
Step 7: Reenable Hibernation If You Need It Later
Changed your mind? You can turn hibernation back on.
Open Command Prompt as an administrator and enter:
powercfg.exe /hibernate on
Press Enter.
Windows should recreate hiberfil.sys as needed. If you want to use Hibernate, you may also need to make the option visible in your power menu.
Open Control Panel > Hardware and Sound > Power Options > Choose what the power buttons do. Select Change settings that are currently unavailable, then check whether Hibernate can be enabled under the shutdown settings.
The exact options can vary by Windows version and device configuration.
Step 8: Check Your Storage Again
Once you’ve completed the change, return to Settings > System > Storage and check your available disk space.
You should see additional free space if hiberfil.sys was successfully removed or reduced.
If you still need more storage, review temporary files, unused applications, and large downloads. Removing hiberfil.sys isn’t always the best solution if other files are responsible for most of your storage usage.
Faqs
Is hiberfil.sys a virus?
No. hiberfil.sys is a legitimate Windows system file when it is located in the expected Windows drive location. If you find a suspicious file with a similar name in an unusual folder, scan it with your security software rather than assuming it is genuine.
Is it safe to delete hiberfil.sys?
Yes, if you disable hibernation through Windows. The recommended method is to run powercfg.exe /hibernate off in an administrator Command Prompt. Windows handles the system configuration and removes the file when appropriate.
Can I delete hiberfil.sys without disabling hibernation?
You should not try to delete it manually. Windows manages this protected system file, and removing it directly is not the correct way to free storage. Use the power configuration command instead.
Will deleting hiberfil.sys make my computer faster?
Not necessarily. Removing the file mainly frees disk space. It does not automatically improve CPU performance, increase RAM, or make every application run faster. Fast Startup may also become unavailable.
Can I delete hiberfil.sys on an SSD?
Yes. The same Windows command works on supported systems with solid-state drives. However, an SSD does not make hiberfil.sys unnecessary. Decide based on your storage needs and whether you use hibernation.
How do I know if hiberfil.sys has been removed?
After running the disable command successfully, check your available storage and, if necessary, inspect the Windows drive with protected system files displayed. You can also run powercfg.exe /a to see which sleep states are available on your computer.
Final Thoughts
hiberfil.sys is not a useless file or a sign that something is wrong with Windows. It supports hibernation and can help Fast Startup work, but it may consume several gigabytes of disk space.
If you rarely use hibernation and need more storage, open an administrator Command Prompt and run powercfg.exe /hibernate off. Windows will disable the feature and remove the file when the command succeeds.
If you want to preserve hibernation, consider reducing the file size only if your system supports it and you understand the limitations.
Ultimately, the best choice comes down to your priorities.
Keep hiberfil.sys if you value hibernation and its convenience. Disable it if you need the storage more than the feature.
Either way, let Windows manage the file through its power configuration tools rather than trying to delete it manually.