Hibernation file (hiberfil.sys)
Also known as: hiberfil.sys, disable hibernation, hibernate file Windows
The hibernation file (hiberfil.sys) is a hidden Windows file that stores the contents of RAM when the PC hibernates, so it can resume exactly where you left off. It is typically several gigabytes and can be removed only by turning hibernation off.
- Stores RAM contents for hibernate
- Usually several GB on the system drive
- Removed with powercfg /hibernate off
What hiberfil.sys is for
When you hibernate, Windows writes everything in memory to hiberfil.sys at the root of the system drive and powers down fully. On the next start it reloads that snapshot, restoring open apps instantly. The file is sized to hold a copy of your RAM, so it is often several gigabytes.
It also backs Fast Startup, the hybrid shutdown that makes Windows boot faster. Disabling hibernation removes the file but turns off both features.
Reclaiming the space
You cannot simply delete hiberfil.sys — it is protected. To remove it, open an elevated Command Prompt and run powercfg /hibernate off, which disables hibernation and deletes the file. Re-enable it with powercfg /hibernate on if you miss hibernate or Fast Startup.