The Disk Cleaner reclaims space the honest way: it scans a fixed, hand-picked allow-list of reclaimable locations — temp folders, browser and shader caches, crash dumps, error reports, the Recycle Bin — clears only the categories you tick, and then re-measures the disk to tell you how many bytes were actually freed. No inflated numbers, no touching your documents, no counting a DNS flush as "disk space".
Every category is a curated entry in an allow-list. Nothing scans your personal files. The categories include:
%TEMP% and C:\Windows\Temp, age-gated so anything written in the last 24 hours survives (an in-progress installer is never disturbed).thumbcache_*.db / iconcache_*.db files; Explorer rebuilds them on demand.C:\Windows\MEMORY.DMP from a BSOD, plus LiveKernelReports.The cleaner deliberately never touches IndexedDB, Local Storage, Cookies or Login Data — the things that hold your signed-in state.
Categories are rated Safe or Caution. Safe categories are selected by default; Caution categories (Windows Update cache, Prefetch, Windows logs, shader caches, launcher and dev caches) start unticked because clearing them has a mild, honest cost — a one-time slower launch, a brief shader recompile, or losing logs that help troubleshoot a flaky PC. Each category shows an Aftermath line spelling out exactly what rebuilds and what (if anything) you give up.
Most cleaners add up the size of what they think they deleted and call that your "freed space". That over-reports: locked or in-use files get skipped, NTFS hardlinks and compression skew the math. BRUTAL instead snapshots free space across your fixed drives before and after the clean and reports the actual difference as verified disk free space gained. If a category couldn't be fully cleared, it stays marked as not-cleared and the log names the likely culprit ("Chrome is open — close it and rescan").
For the largest legitimate system reclaim, the cleaner can run an Analyze of the Windows component store (WinSxS) read-only, and — if cleanup is recommended — a Deep Windows cleanup that runs DISM /StartComponentCleanup through the in-box Windows engine. It creates a system restore point first and never hand-deletes WinSxS (which would break Windows).
/ResetBase, so recent updates stay uninstallable). A restart may be needed afterward. Free for everyone since 7.4.0 - Windows already schedules this itself under Automatic Maintenance, so charging for it amounted to charging for "sooner". You start it yourself and confirm first.To find where your space went in the first place, pair this with the Disk Analyzer. To remove folders left behind by uninstalled apps, see Install Residue.
Will Disk Cleaner delete my files, passwords or browsing history?
No. It only clears a fixed allow-list of caches, temp folders, dumps, logs and the Recycle Bin. Browser logins, cookies, history, IndexedDB and Local Storage are explicitly never touched, and it never scans your documents.
Why is the freed number sometimes smaller than the scanned estimate?
Because we report the verified before/after disk delta, not an optimistic sum. Locked or in-use files are skipped, and the age gate protects files newer than 24 hours. The smaller number is the true one.
Can I undo a clean?
Junk removal is permanent (recycling temp files wouldn't reclaim space), so it can't be undone — only the Recycle Bin category empties the bin. That's why Caution categories start unticked and each shows exactly what rebuilds. For recoverable deletes of large files, use the Disk Analyzer, which routes deletes through the Recycle Bin.
Is the Deep Windows (DISM) cleanup safe?
Yes — it runs the in-box Windows servicing engine, creates a restore point first, and never hand-deletes WinSxS. It is one-way and non-cancellable once started because DISM must finish servicing the OS, so only start it when you can let it complete.