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:\Windows manually.

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)

  1. Open Command Prompt as administrator (right-click Start › Terminal (Admin)).
  2. Run powercfg -h off.
  3. Reboot. The hiberfil.sys file 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

  1. Open Command Prompt as administrator.
  2. Run DISM.exe /Online /Set-ReservedStorageState /State:Disabled.
  3. 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

  1. Press Windows + R, type sysdm.cpl, press Enter.
  2. Go to the Advanced tab › Performance › Settings › Advanced › Virtual memory › Change.
  3. 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.

For your phone, Cleanor for iPhone finds large videos, duplicate photos, and heavy caches in one on-device pass — nothing uploaded.