What is hiberfil.sys?
C:\hiberfil.sys stores the contents of memory when the PC hibernates. Windows also uses it for Fast Startup. Its size depends on your RAM and is often several gigabytes.
The file is hidden and protected. It can't be deleted in File Explorer, but it disappears when you turn off hibernation.
Delete hiberfil.sys
- Right-click Start → Terminal (Admin).
- Type this and press Enter:
powercfg /hibernate off
Windows removes hiberfil.sys right away. You can turn hibernation back on at any time with powercfg /hibernate on. Microsoft lists every option in Powercfg command-line options.
What you lose:
- hibernation (sleep still works),
- Fast Startup, which makes Windows boot a little faster after shutdown. On PCs with an SSD the difference is usually small.
On laptops you often close for long periods, hibernation can be useful because it uses no battery. Weigh it up there.
Remove hiberfil.sys with DiskDetox
DiskDetox lists hiberfil.sys in the optional Windows clean-up when the file exists, with its size and an explanation of what you give up. Only after you confirm, and with administrator permission, does it turn off hibernation with powercfg. The page file is always left alone. Other big system folders are Windows.old and WinSxS; for an overview see free up disk space.
Find hidden space hogshiberfil.sys, Windows.old and update leftovers, each with what it means to remove them.
What is pagefile.sys, and why should it stay?
C:\pagefile.sys is the page file. Windows moves data there when memory runs low and needs it for crash reports. Without it, programs can crash when memory is full.
- Don't delete it or turn it off, even if guides online say so.
- Best let Windows manage its size (Control Panel → System → Advanced system settings → Performance → Settings → Advanced → Virtual memory).
- If you have a second internal drive, you can put the page file there. For most people it isn't worth it.
Frequently asked questions
Is turning off hibernation harmful?
No. Windows keeps working normally; only hibernation and Fast Startup are gone. Sleep and shutdown still work.
Can I shrink hiberfil.sys instead of deleting it?
Yes. With powercfg /h /type reduced Windows keeps a smaller file for Fast Startup only; hibernation itself is then no longer available.
Why is hiberfil.sys back after an update?
Some feature updates turn hibernation back on. Just run the command again.