Quick fix: Open Command Prompt (Admin). Run: powercfg /hibernate off. The hiberfil.sys file (often 4-10GB+) is deleted. Hibernate is now disabled. You won’t see Hibernate in the Power menu. Sleep mode still works. To re-enable: powercfg /hibernate on.

The hibernation file (hiberfil.sys) stores RAM contents on disk when you hibernate, so the PC can resume to your exact state. By default, it’s 40-75% of your RAM size. On an SSD-tight system, that’s gigabytes of wasted space. If you don’t hibernate (only Sleep and Shut Down), turn it off to reclaim space.

Symptom: Want to disable hibernation on Windows 11 to free up C: drive space.
Affects: Windows 11 (and Windows 10).
Fix time: ~2 minutes.

What causes this need

Hibernation reserves disk space equal to ~40-75% of RAM. For 32GB RAM, that’s 12-24GB. Useful if you actually hibernate. Disabling it saves disk space and disables the hybrid sleep (which uses hibernation as a fallback for sleep mode). Sleep still works (RAM stays powered).

Method 1: Disable via powercfg

The standard route.

Open Command Prompt as Admin (or Terminal as Admin).
Run:
```
powercfg /hibernate off
```
This deletes C:\hiberfil.sys and disables Hibernate.
Free space increases (check Settings → System → Storage).
Verify: powercfg /a. Lists available sleep states. Hibernate should no longer be listed.
Power menu: open Start → Power button. Sleep and Shutdown shown; no Hibernate option.
Note: Fast Startup also depends on hibernation. Disabling hibernation also disables Fast Startup. Boot times may be 1-2 seconds slower — usually unnoticed.

This is the standard fix.

Method 2: Reduce hibernation file size instead of disabling

For partial space recovery.

If you want to keep hibernation but reduce file size: use powercfg’s /size option.
Hibernation file can be set to:
- Full (default): 40-75% of RAM. Full hibernation possible.
- Reduced: 20-25% of RAM. Fast Startup works; full hibernation doesn’t.
To set Reduced:
```
powercfg /hibernate /size 25
```
(percentage: 25% of RAM)
You keep Fast Startup but lose explicit hibernation.
To set back to full: powercfg /hibernate /size 0 (default = max).
For specific size in MB:
```
powercfg /hibernate /type reduced
```
Check current size: powercfg /a — or look at hiberfil.sys size in C:.

This is for partial reclaim.

Method 3: Disable Fast Startup separately

For keeping hibernation but disabling Fast Startup.

Some users want hibernation but find Fast Startup causes issues (slow shutdown, network adapter problems).
Open Control Panel → Power Options → Choose what the power buttons do.
Click Change settings that are currently unavailable.
Under Shutdown settings: untick Turn on fast startup (recommended).
Click Save changes.
Fast Startup is off. Hibernation still works. Hibernation file remains.
For chronic issues: Fast Startup off solves: failed network adapter wake, BIOS access issues after shutdown, dual-boot bootloader confusion.
To re-enable: same path, re-tick the option.

This is the alternative route.

How to verify the fix worked

Check C: free space. Increased by hiberfil.sys size.
powercfg /a doesn’t list Hibernate.
Settings → System → Storage: Hibernation file entry shows 0 bytes or is gone.
Power menu: Hibernate option not shown.

If none of these work

If hiberfil.sys persists: Group Policy enforces hibernation: corporate-managed PCs may force hibernation on. Check with IT. For Surface devices: hibernation tightly integrated; disabling may cause issues. Test thoroughly. For laptops with Modern Standby (S0): hibernation rarely used; disabling has no downside. For desktops: hibernation rare, disable freely. For removed Hibernate option but file remains: reboot. Or delete hiberfil.sys via cmd: del /f /a C:\hiberfil.sys (with hibernation disabled). For Surface Pro / hybrid devices: some require hibernation for Modern Standby S4 transitions; check vendor documentation.

Bottom line: powercfg /hibernate off in Admin Command Prompt. Reclaims 4-10GB+ on C:. Sleep mode still works. To partial-reclaim: powercfg /hibernate /size 25 keeps Fast Startup but reduces hibernation file size.