How to Delete Hiberfil.sys and Reclaim Disk Space on Windows

If you've ever dug into your Windows drive looking for space hogs, you've probably stumbled across a massive file sitting quietly at the root of your C: drive — hiberfil.sys. It can easily consume several gigabytes, and it's not immediately obvious what it does or whether you can safely remove it.

Here's what you need to know before touching it.

What Is Hiberfil.sys?

Hiberfil.sys is a system file created and managed by Windows to support hibernation. When your PC hibernates, Windows dumps everything currently in RAM — open apps, system state, active processes — into this file on disk. When you power back on, Windows reads that file and restores your session exactly as you left it, without going through a full boot sequence.

The file's size is directly tied to your total installed RAM. On a system with 16 GB of RAM, hiberfil.sys will typically be around 12–14 GB. More RAM means a larger file.

Windows also uses hiberfil.sys to support a feature called Fast Startup (introduced in Windows 8 and carried through Windows 10 and 11). Fast Startup isn't full hibernation — it saves only the kernel session, not your open apps — but it still depends on this file being present.

Why You Might Want to Delete It

The most common reason is straightforward: reclaiming disk space, especially on systems with smaller SSDs (128 GB or 256 GB drives). When storage is tight, a 10–15 GB system file that you've never consciously used becomes a reasonable target.

Other situations where deletion makes sense:

• You never use hibernation and always shut down or use sleep mode instead
• You're running a desktop PC that's always plugged in and never needs to preserve session state across power-offs
• You're using a dual-boot setup where hiberfil.sys can occasionally cause filesystem conflicts
• You're troubleshooting sleep/wake issues where hibernation is a known contributor

How to Delete Hiberfil.sys 💻

You cannot delete hiberfil.sys directly through File Explorer — Windows locks the file while it's in use. The correct method is to disable hibernation through the command line, which causes Windows to remove the file automatically.

Step-by-Step: Disable Hibernation via Command Prompt

1. Press Windows + S and search for Command Prompt
2. Right-click it and select Run as administrator
3. Type the following command and press Enter:

powercfg /hibernate off 

That's it. Windows will immediately disable hibernation and delete hiberfil.sys without requiring a restart. You can verify the file is gone by navigating to your C: drive root (you may need to enable Show hidden items in File Explorer's View settings).

Re-enabling Hibernation Later

If you change your mind, the process reverses just as cleanly:

powercfg /hibernate on 

Windows recreates hiberfil.sys immediately after running this command.

What Disabling Hibernation Actually Changes

This is where the decision gets more nuanced, depending on your setup.

Sleep mode and hibernate are different. Sleep keeps your session in RAM with the PC drawing a small amount of power. Hibernate writes everything to disk and cuts power entirely. Disabling hibernation does not affect sleep — your PC can still sleep normally.

Fast Startup is the piece most users don't anticipate losing. It's a hybrid shutdown mode that makes Windows start faster by partially hibernating the kernel on shutdown. On an SSD, the difference is often minimal. On a traditional HDD, Fast Startup can make a more noticeable difference in boot times.

Variables That Affect Whether This Is the Right Move 🔍

Not every setup looks the same. A few factors meaningfully shift the calculation:

RAM size — The more RAM you have, the larger hiberfil.sys is, and the more space you stand to recover. On a 32 GB system, the file might consume 24+ GB.

Drive type and capacity — On a 500 GB or 1 TB SSD, losing 12 GB is barely noticeable. On a 128 GB drive that's nearly full, it's significant.

Laptop vs. desktop — Laptops benefit more from hibernation because they run on battery and may be closed and stored for extended periods. Desktops, which are always plugged in, rarely need true hibernate functionality.

OS version and use case — Windows 11 handles Fast Startup and sleep states somewhat differently than Windows 10 in certain configurations. If you rely on quick boots and have an older HDD, disabling hibernation may noticeably affect your daily experience.

Dual-boot systems — Users running Windows alongside Linux often find that hiberfil.sys causes read access issues with the Windows partition from Linux. In that context, disabling hibernation is frequently recommended anyway.

A Note on Safe Mode and Reduced Functionality Versions of hiberfil.sys

Windows 10 and 11 also support a reduced-size hibernation file — a middle ground that preserves Fast Startup without allocating the full RAM-sized file. You can set this with:

powercfg /hibernate /size 40 

This sets the file to 40% of your RAM size, which is enough to support Fast Startup but not full hibernate. It's an option worth knowing about if you want some of the benefits without the full storage cost.

The Real Decision Point

Whether deleting hiberfil.sys is worth it comes down to how you actually use your machine day-to-day — how often you hibernate, whether Fast Startup matters to your workflow, how tight your storage really is, and whether you're on a laptop or a desktop. The command to remove it takes five seconds. Understanding what you're giving up beforehand is where your own setup becomes the deciding factor.