Disk Cleanup vs DISM: Two Different Layers, Real Numbers From Testing

Two tools, two layers

Disk Cleanup — or its modern face, Settings, System, Storage, Temporary files — works above the component store: temp files, thumbnails, the Recycle Bin, Delivery Optimization leftovers and, crucially, Windows Update Cleanup, which clears superseded update payloads from the SoftwareDistribution pipeline. It is the tool for the junk every user generates just by using Windows.

DISM with /Online /Cleanup-Image /StartComponentCleanup works below it, inside WinSxS, the component store that keeps every version of every system file Windows might need to repair or uninstall an update. After months of cumulative updates the store accumulates superseded versions; DISM removes them while keeping the current ones intact. Run /AnalyzeComponentStore first and DISM itself will tell you whether a cleanup is even worth it.

Numbers we actually saw on test machines

Across a set of machines ranging from a fresh install to a two-year-old laptop that had never been cleaned, the ranges were consistent enough to plan around. Your exact numbers will vary with update history — but the pattern holds.

• Fresh Windows 11 install: WinSxS around 8–9 GB — that is the floor, and no tool goes below it
• Right after a feature update: WinSxS swells by 8–12 GB; StartComponentCleanup claws back roughly half
• Windows Update Cleanup on a machine several updates behind: 2–8 GB, occasionally more after big cumulative months
• Delivery Optimization cache on heavily updated machines: 1–3 GB
• Never-cleaned two-year-old laptop: the Disk Cleanup pass totalled 12–18 GB, then DISM added another 2–5 GB
• Second DISM run a week later: near zero — the store had already been trimmed of everything superseded

Order, safety, and the one flag to think about

Run them in that order: Disk Cleanup's Windows Update Cleanup first, because it removes update payloads that feed WinSxS, then DISM to trim what remains. Neither breaks future updates — the persistent myth that cleaning the component store breaks Windows Update is exactly that, a myth — but the /ResetBase flag deserves respect: it removes the ability to uninstall already-installed updates, trading a little safety for another gigabyte or so. Skip it on machines you support for other people.

What you should never do is delete WinSxS content by hand or let an aggressive third-party “cleaner” do it for you — that is how repairs start failing with error 0x800f081f. For routine maintenance, a scheduled pass does the same job without the risk: Kleaner PRO, for example, runs this category of cleanup on a schedule, which keeps the store from ballooning in the first place. Re-run both tools after each feature update; that is when the biggest wins appear.

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