The System & reserved category in Windows 11 often shows 20-40 GB because it is not one file but the sum of four separate allocations the operating system sets aside for itself: core system files, Reserved Storage for updates, the paging file, and the hibernation file. If you opened Settings › System › Storage and were alarmed by that number, most of it is normal, and parts of it can be safely reduced.
TL;DR
- System & reserved = system files + Reserved Storage +
pagefile.sys+hiberfil.sys. - Turning off hibernation (
powercfg -h off) is the biggest safe win, often 4-12 GB. - Disabling Reserved Storage frees ~7 GB but makes future feature updates riskier on a tight drive.
- Capping the page file recovers a few GB; never set it to zero.
- Never delete core system files in
C:\Windowsmanually.
What is inside "System & reserved" on Windows?
The System & reserved category groups four distinct allocations:
| Component | What it is | Typical size | Safe to remove? |
|---|---|---|---|
| System files | The OS itself: C:\Windows, drivers, core binaries |
15-25 GB | No |
| Reserved Storage | Space held back so feature updates can install (Windows 10 1903+) | ~7 GB | Yes, with caution |
Page file (pagefile.sys) |
Virtual memory; scales with installed RAM | 2-16 GB | Cap, do not delete |
Hibernation file (hiberfil.sys) |
RAM snapshot for hibernation and Fast Startup | 40-75% of RAM | Yes |
Knowing which bucket your gigabytes fall into tells you which lever to pull.
How do I shrink each part of System & reserved?
Work through these from biggest payoff to smallest, and only do the ones that fit how you use the machine.
Turn off hibernation (biggest win on high-RAM laptops)
- Open Command Prompt as administrator (right-click Start › Terminal (Admin)).
- Run
powercfg -h off. - Reboot. The
hiberfil.sysfile is removed.
This disables hibernation and Fast Startup; normal Sleep still works. On a 16 GB laptop this typically frees 6-12 GB.
Disable Reserved Storage
- Open Command Prompt as administrator.
- Run
DISM.exe /Online /Set-ReservedStorageState /State:Disabled. - Reboot.
This frees roughly 7 GB but means a future feature update may fail if your drive is nearly full at update time. Re-enable it later with /State:Enabled.
Cap the paging file
- Press Windows + R, type
sysdm.cpl, press Enter. - Go to the Advanced tab › Performance › Settings › Advanced › Virtual memory › Change.
- Untick Automatically manage, then set a custom maximum (for example 4096 MB on systems with 16 GB+ RAM).
Do not set the page file to zero. Windows and some applications rely on it and will crash or refuse to launch.
Is it safe to shrink System & reserved storage?
The three actions above are reversible and safe for typical users, with trade-offs: no hibernation means no resume-from-hibernate, disabled Reserved Storage means tighter feature updates, and a capped page file can cause issues if you run very memory-heavy apps. What is never safe is manually deleting files inside C:\Windows, the System32 folder, or the drivers directory. These are the core system files that keep Windows bootable; removing them can leave the machine unable to start. If you want guaranteed recoverability, create a restore point before changing the page file or Reserved Storage.
How much space can I realistically reclaim?
On a typical 16 GB laptop, turning off hibernation recovers 6-12 GB, disabling Reserved Storage adds ~7 GB, and capping an oversized page file can recover a few more. Combined, that is often 15-20 GB back from a single sitting, without touching a single personal file. If your drive is still tight afterward, the remaining pressure is usually elsewhere: temporary files, leftover installers, large media, or unused desktop applications.
FAQ
What is the "System & reserved" category in Windows 11?
System & reserved is a storage grouping that combines the core operating-system files, Reserved Storage set aside for updates, the virtual-memory paging file, and the hibernation file. It commonly totals 20-40 GB, most of which is normal and expected.
Can I delete the hibernation file to save space?
Yes. Run powercfg -h off from an administrator Command Prompt and reboot to remove hiberfil.sys. This disables hibernation and Fast Startup but keeps normal Sleep working, and it is fully reversible with powercfg -h on.
Is it safe to disable Reserved Storage?
Disabling Reserved Storage frees about 7 GB and is safe day to day, but it removes the buffer Windows uses to install feature updates. On a nearly full drive, a future update could fail until you free space. You can re-enable it at any time.
Should I delete the pagefile.sys file?
No. The page file is active virtual memory; deleting or zeroing it can cause crashes and apps that refuse to launch. Instead, cap its maximum size through System Properties › Virtual memory if it is unusually large.
Why does System & reserved keep changing size?
Reserved Storage and the page file expand and shrink as Windows stages updates and manages memory, so the category naturally fluctuates over time. A moving number is normal and does not indicate a problem.
For the single highest-impact step on a laptop, follow the full walkthrough on disabling hibernation to save gigabytes. To go further with native tools, see deep-cleaning Windows 11/10 without third-party utilities and learn whether compressing the C drive is safe. To find the largest remaining offenders, What is TreeSize Free and how to use it maps your disk visually. For a broader overview of where to start, see the clean up phone storage solution hub.