When disk space gets critically low on Windows 11, the consequences are real: Windows Update can’t download patches, applications crash on temporary file writes, the system page file can’t expand, and browser performance degrades as cache gets constrained. “Low disk space” isn’t just a notification to dismiss — it’s a warning that Windows is starting to fail at background tasks you depend on. If you want the full context, see our Windows 11 How-To Guides.
The fastest wins are usually temporary files and the Recycle Bin. These alone often recover several gigabytes in five minutes with zero risk of deleting anything important. Start there before touching anything else.
Temporary files — the quick win
Settings → System → Storage → “Temporary files” → Windows scans and presents categories with their sizes. The safe categories to delete:
- Temporary files: application temp files that accumulate over time
- Recycle Bin: files you’ve deleted but not permanently removed
- Thumbnails: cached image previews (rebuilt automatically as needed)
- Windows error reports: crash logs sent to Microsoft
- DirectX shader cache: GPU shader programs that will rebuild automatically
- Delivery optimisation files: Windows Update files shared with other PCs on the network
The category that can be large but requires caution: “Previous Windows installations” — if Windows was recently upgraded, this stores the previous version for rollback. It can be 10-30GB. Safe to delete if you’re satisfied with the current Windows version and more than 10 days past the upgrade; the 10-day rollback window will have passed.
Storage Sense — automated ongoing management
Settings → System → Storage → Storage Sense → toggle On → then configure it. When active, Storage Sense automatically deletes temporary files on a schedule, empties the Recycle Bin after a set period, and removes downloaded files that haven’t been used for a specified duration. “Configure Storage Sense” at the bottom of the settings shows the schedule options.
For most users: run monthly, delete Recycle Bin contents after 30 days, delete downloads not used in 60 days. This prevents the gradual accumulation of temporary files that causes low-space warnings over time. Set it once and let it run — it won’t delete anything it hasn’t been told to delete.
Finding what’s actually using space
Settings → System → Storage → “Other” section → “View” → shows all folder sizes on the system drive. The “Other users” section shows space used by other user profiles. The “Windows” folder shows OS files. “Apps & features” shows installed application sizes.
For a more detailed breakdown: WinDirStat or TreeSize Free (both free, both excellent) scan the drive and produce a visual map showing exactly which folders and files are largest. This identifies surprising space consumers that Windows’ built-in storage view doesn’t highlight — a game’s save files in AppData, a virtual machine disk image, a year of accumulated downloads, or a video editing project left in a temp folder.
Applications — uninstalling vs compressing
Settings → Apps → Installed apps → sort by Size (click the “Sort by” dropdown) → identifies the largest applications. Before uninstalling anything: make sure you’re not actively using it and that you can reinstall it if needed. Steam games, Adobe applications, and developer tools are typically the largest entries and the clearest candidates for removal on constrained storage.
For applications you want to keep but use infrequently: some apps support “Archive” — Settings → Apps → three dots next to the app → “Archive app.” Archived apps retain their data and settings but remove the executable files, freeing space. Opening the app restores it automatically. Not available for all apps, but useful for Microsoft Store apps with large footprints.
OneDrive and Files On-Demand
If you use OneDrive: Files On-Demand stores files in the cloud with local placeholders. Files that haven’t been accessed recently appear as cloud icons in File Explorer, consuming minimal local space. Files you use regularly stay downloaded locally. Right-click any file → “Free up space” moves it back to cloud-only. Right-click a folder → “Free up space” applies to everything in it.
For machines with small SSDs (128-256GB): moving large file categories (photos, videos, archives) to OneDrive with Files On-Demand can effectively multiply available local storage without deleting anything. The trade-off: those files require internet access to open, and first-open after moving involves a download delay.
Page file and hibernation file
Two Windows files that consume significant space without appearing in Storage settings:
Hiberfil.sys (hibernation file) — typically equal to installed RAM size (8GB RAM = 8GB file). If you don’t use hibernation (you restart or use sleep instead): Admin Command Prompt → powercfg /hibernate off. This deletes the hibernation file and reclaims that space. Note: disabling hibernation also disables Fast Startup. If boot speed matters: leave hibernation on.
Pagefile.sys (virtual memory page file) — usually 1.5× RAM or more. Don’t delete or disable this; Windows needs it. But if System-managed page file is on a nearly-full drive: consider moving it to a secondary drive. Advanced system settings → Performance → Settings → Virtual Memory → change to a drive with more free space.
Our guide on Windows 11 performance optimisation covers storage-related performance alongside other system speed factors, and our Windows 11 backup strategies covers moving data to external storage as part of a backup plan that also frees local space. For a complete guide to Windows 11 storage components, Microsoft’s storage documentation covers page files, hibernation, and the storage subsystem in technical detail.
Downloads folder and Desktop
Two locations that accumulate files invisibly over time: Downloads and the Desktop. The Downloads folder on a machine used for a year or two might contain gigabytes of installers, ZIPs, PDFs, and other files that were needed once and forgotten. Sorting by Date modified shows what’s oldest and most likely safe to delete. Right-click column header in File Explorer → Size also shows file sizes without needing to open each one.
The Desktop stores files directly in the user profile’s desktop folder, which is backed up by OneDrive if Desktop sync is enabled. Files on the Desktop aren’t in any particular location for archival, and clearing it periodically is good habit — moving project files into actual project folders and deleting one-off files clears both clutter and storage.
Disk Cleanup — the legacy tool
Win+S → “Disk Cleanup” → runs the classic tool that’s been in Windows since XP. It overlaps with Storage Sense’s temporary file cleaning but adds an option that Storage Sense doesn’t have direct access to: “Clean up system files” (run as administrator) → clears Windows Update cleanup files, old Windows versions, service pack backups, and other system-level temporary data.
After running Disk Cleanup with system files included: a restart usually required for the “Windows Update Cleanup” category to be fully committed. This can recover several gigabytes on machines that have received many cumulative updates.
| Space source | Typical size | How to reclaim |
| Temporary files | 1-10 GB | Settings → Storage → Temporary files |
| Recycle Bin | Variable | Empty Recycle Bin / Storage Sense |
| Previous Windows installation | 10-30 GB | Storage → Temporary files (if >10 days post-upgrade) |
| Hibernation file | Equal to RAM size | powercfg /hibernate off (if not using hibernation) |
| Downloads folder | Variable (often 2-20 GB) | Manual review and deletion |
| Unneeded applications | Variable | Settings → Apps → sort by size → uninstall |
| Windows Update cleanup | 1-5 GB | Disk Cleanup → Clean up system files |
The temporary files and previous Windows installation together provide the most storage recovery with the least risk. The hibernation file is the next largest guaranteed recovery if you don’t use hibernation. Downloads and application cleanup require more judgement but often yield the most space overall. The combination of Storage Sense for ongoing management and an occasional WinDirStat scan to find unexpected large files keeps storage under control without crisis-mode cleanups.
DISM for Windows Update component store
The Windows Update component store (WinSxS folder in C:Windows) accumulates superseded update components over time. Windows manages this automatically, but running DISM cleanup manually can reclaim additional space beyond what Disk Cleanup provides:
DISM /Online /Cleanup-Image /StartComponentCleanupRun in an elevated Command Prompt. This command identifies and removes superseded update components that Windows no longer needs. Can take 20-45 minutes on machines with large component stores. Follow with a restart. The space recovered varies by how long the machine has been running and how many updates have accumulated — anywhere from a few hundred MB to several GB.
Developer and build system files
For developers: build systems, Docker, and development tools create significant storage footprints that grow silently:
- Docker images and containers: Docker Desktop → Volumes → prune unused volumes. docker system prune removes stopped containers, unused images, and dangling volumes. Docker data can grow to 10-50GB on active development machines.
- npm cache: npm cache clean –force. The npm cache (typically in AppDataRoamingnpm-cache) grows with each package installation and rarely needs retention.
- Build output folders: bin, obj, target, dist, build — these are regenerated from source. Safe to delete when the project isn’t actively being compiled.
- Conda/pip environments: Python virtual environments accumulate separately and can be recreated from requirements files when needed.
Using Compact OS to compress Windows
On machines with genuinely constrained storage (64GB SSDs, which are common on budget laptops): Compact OS compresses Windows installation files to reduce their footprint by 1.5-2GB. Admin Command Prompt:
compact /CompactOS:alwaysThe compression is transparent — Windows reads compressed files without any visible performance difference on modern hardware. To reverse it: compact /CompactOS:never. This is a reasonable option when storage is critically constrained and other cleanup measures have been exhausted. Not recommended as a first measure, but useful as a last resort on 64GB drives.
External storage as the capacity solution
When cleaning provides temporary relief but the drive is structurally too small for your usage: external storage is the correct answer. Options by use case:
- External SSD (USB 3.1/3.2): fast enough for active project storage, photo libraries, and video work. Transfer speeds of 400-1000 MB/s make working directly from external SSD practical.
- USB HDD: much slower than SSD but fine for cold storage — archives, backups, media libraries that are accessed occasionally rather than constantly.
- microSD card: on laptops with SD card slots: a high-endurance microSD card can provide persistent additional storage that sits flush in the slot and is effectively invisible. Slower than an SSD but faster than you might expect for sequential reads.
- NAS device: for households with multiple machines: a Network Attached Storage device provides shared central storage accessible by all machines over the network.
For machines where the internal drive simply can’t hold everything needed: the right long-term answer is either adding external storage or, where the machine supports it, upgrading the internal SSD. Many laptops allow replacing the M.2 SSD with a larger one; this is typically a 30-minute operation that doubles or quadruples available storage. Storage prices have fallen considerably — 2TB M.2 SSDs now cost under £100. On a machine that will be used for several more years, an internal upgrade often costs less than the ongoing friction of managing tight storage. See also Windows 11 Device Manager for a related case.
Regular storage maintenance habits
Storage problems are mostly a maintenance failure rather than a capacity problem. A machine that’s regularly cleaned and organised handles the same amount of work in half the storage of one left unmanaged. A few habits that prevent crisis-level low storage:
- Enable Storage Sense — handles temp files and Recycle Bin automatically
- Review Downloads monthly — delete installers, ZIPs, and files downloaded for a one-time purpose
- Uninstall games and applications after finishing with them rather than leaving them installed indefinitely
- Move photos from phone to PC and then to cloud backup or external storage rather than accumulating on both
- Use WinDirStat or TreeSize twice a year to spot new large file accumulations before they become critical
The pattern on most low-storage machines when you actually look: several large legitimate files (game library, photo archive, work project files), plus a substantial amount of accumulated junk (temp files, downloads, old installers, orphaned application data). The legitimate large files require active decisions (use external storage, upgrade SSD, move to cloud). The accumulated junk can be cleared immediately with no consequence. Separating these two categories makes storage management straightforward: address the junk first for quick wins, then make considered decisions about the legitimate large content. You might also run into Windows 11 Disk Management.
