Windows quietly parks a hidden file called hiberfil.sys on your system drive, and on a small SSD it can swallow several gigabytes you would rather use for games. Disabling hibernation reclaims that space instantly, but it also changes how fast startup and sleep behave. Here is what the file does and when turning it off is the right call.
What hiberfil.sys actually stores
Hibernation writes the entire contents of your RAM to disk so the machine can power off completely and resume exactly where you left off. Because it mirrors memory, the file scales with how much RAM you have. Windows also uses this same file for Fast Startup, the feature that makes a cold boot feel quick by saving the kernel session.
How big is it?
| Installed RAM | Typical hiberfil.sys size |
|---|---|
| 8 GB | ~3 GB |
| 16 GB | ~6 GB |
| 32 GB | ~10-13 GB |
| 64 GB | ~20-26 GB |
By default Windows sizes the file at roughly 40 percent of RAM, though full hibernation can push it higher. On a 64 GB desktop with a 256 GB boot drive, that is a meaningful chunk of the volume.
The trade-off
Turn hibernation off with an elevated command (powercfg /hibernate off) and the file disappears, freeing the space. The cost is that you lose true hibernate, and Fast Startup stops working, so cold boots take a few seconds longer. On a desktop that mostly uses Sleep (which keeps RAM powered and does not need the file), that cost is close to zero.
When to keep it
Laptops benefit from hibernation because it survives a dead battery without losing your session, and it draws no power while parked. If you regularly close the lid for hours or travel, leave hibernation enabled and instead shrink the file to Fast-Startup-only size with powercfg /h /type reduced, which roughly halves it.
Does it wear out the SSD?
Every hibernate writes gigabytes to the drive, so heavy daily hibernation adds to total bytes written. Modern SSDs are rated for hundreds of terabytes written, so even a hibernate-heavy laptop will not hit the endurance wall for many years. Space, not wear, is the real reason to disable it on a small drive.
Sleep, hibernate, and hybrid sleep
It helps to know the three power states. Sleep keeps your session in RAM and draws a trickle of power, resuming almost instantly, and it does not need the hibernation file. Hibernate writes RAM to disk and powers off completely, using zero power but requiring hiberfil.sys. Hybrid sleep, common on desktops, does both at once so an unexpected power loss during sleep does not lose your work.
Reclaiming the space step by step
Open an elevated command prompt and run the hibernate-off command; the file vanishes and the space is freed immediately, no reboot required. If you later miss the feature, turn it back on with a single command. This reversibility is why disabling hibernation is a low-risk experiment: try it, see whether you ever miss true hibernate, and switch it back in seconds if you do.
Quick reference
Decide quickly whether disabling hibernation suits your machine:
- The hiberfil.sys file is roughly 40 percent of your RAM, so 6-25 GB on typical systems.
- Desktops that rely on Sleep lose nothing but a slightly slower cold boot.
- Laptops should keep hibernation to survive a dead battery without losing the session.
- Reduced mode keeps Fast Startup while roughly halving the file’s size.
- The change is instant and fully reversible with a single command, so it is low-risk to try.
FAQ
Will disabling hibernation slow down my PC?
Only your cold boot, because Fast Startup relies on the same file. Sleep and normal use are unaffected, and on a fast NVMe drive the extra boot time is usually two to five seconds.
Can I move the hibernation file to another drive?
No. Windows requires hiberfil.sys on the system volume and does not let you relocate it. Your only options are shrinking it, using reduced mode, or disabling it entirely.
Bottom line
On a desktop with a small SSD that lives on Sleep, disabling hibernation is an easy way to reclaim 6 to 25 GB with no real downside beyond a slightly slower cold boot. On a laptop, keep it but consider reduced mode. The wear concern is overblown; space is the deciding factor.
