Clear the Cache on a PC? There Are Five of Them

Somebody told you to clear your cache. They did not say which one, because they probably did not know there was more than one.

Windows keeps at least five, they fix completely different problems, and the one you were told to clear is usually not the one holding your space.

I measured all five on this machine. They came to nearly two gigabytes, and two thirds of that sits in a folder nobody means when they say the word.

The five, and what each one is actually for

Read this list once and the advice you were given will make sense. The browser cache holds copies of web pages. You clear it when a website looks broken or shows you an old version.

The temp folder holds working files that programs left behind, and you clear it when your drive is filling up. The Windows Update cache holds downloaded update files, cleared when an update refuses to install.

The thumbnail and icon caches hold little pictures of your files, cleared when thumbnails go wrong or icons turn blank, and the DNS cache holds remembered addresses for websites, cleared when one site will not load.

Ours: what each one weighed here

Five numbers, and the shape of them is the surprise. Ours, measured on this machine: the temp folder holds 1,320 MB across 8,638 files, easily the biggest of the five.

The thumbnail cache came second at 383 MB, spread over fifteen database files, then the Windows Update cache at 240 MB across 41 files, and the icon cache at 13 MB.

The DNS cache held 107 remembered addresses, which weighs nothing at all and is not about space. Nearly two gigabytes in total, and about two thirds of it is temp files. Not your browser.

Read your own in one line

Thirty seconds, and it changes what you go and clear. Open Terminal and run this for your temp folder:

(Get-ChildItem $env:TEMP -Recurse -File -ErrorAction SilentlyContinue | Measure-Object Length -Sum).Sum / 1MB

Then run `ipconfig /displaydns` to see the DNS side. It prints every address your PC currently remembers. Ours: my Windows temp folder was completely empty while the user one held 1.3 GB, and the two fill up very differently.

Which one to clear, by symptom

Match the fault, not the advice. A website showing old content or looking broken means the browser cache, held per browser. One site unreachable while everything else works means the DNS cache, cleared with `ipconfig /flushdns`.

A drive filling up means the temp folder, documented by Microsoft through Storage settings and Disk Cleanup.

That is where the space actually is. Blank or wrong thumbnails mean the thumbnail cache, which Windows rebuilds on its own once cleared.

An update that downloads and then fails means the Windows Update cache. The error code it gives you narrows it further.

The safe way to clear the big ones

Two routes, and I would use the first.

Microsoft documents the safe route on its free up drive space page: Storage settings, then Temporary files.

Windows ticks what is safe, shows you the size, and then does the deleting itself.

Disk Cleanup, also Microsoft's own tool, reaches the update cache and the thumbnail cache, and its second button reaches more.

Do not install a cleaning program to do any of this, when every one of these is a built-in setting or a single command.

Ours: do not delete files out of the temp folder by hand while things are running. Some of them are in use, and Windows will simply refuse rather than break, but you will think it did not work.

We could not find a single Microsoft page that lists all five caches together, which is exactly why the advice you were given did not say which one.

What clearing a cache will not do

Three expectations worth correcting. It will not speed up your PC. A cache exists to make things faster, and emptying it makes the next few minutes slower, on purpose.

It will not fix a slow machine either. That is a different measurement and it usually names something specific.

And it will not free space permanently. Everything you just cleared starts filling up again immediately, which is the whole point of a cache.

Ours: clear a cache to fix a symptom, not as maintenance, and there is no health benefit to an empty one.

Status: measured here on 26 August 2026, on Windows 11, against Microsoft's storage guidance. The Delivery Optimization cache needs elevation to read, so it is not in the totals.

Which cache should I clear on Windows?

It depends entirely on the symptom. A broken website means the browser cache. A full drive means the temp folder. A failing update means the Windows Update cache.

Wrong thumbnails mean the thumbnail cache. One unreachable site means the DNS cache. Clearing the wrong one changes nothing.

Will clearing the cache make my PC faster?

No, and it usually does the opposite for a while. A cache exists so your PC does not have to fetch or rebuild something twice.

Emptying it means everything has to be done again from scratch. Clear one to fix a specific symptom, never as routine maintenance.

How much space do the caches actually take?

On the machine measured here it came to roughly two gigabytes, and about two thirds of that was the temp folder rather than anything to do with browsing.

The thumbnail cache was 383 MB and the Windows Update cache 240 MB. Your own split will differ, so measure before you assume.

Is it safe to delete temporary files?

Yes, through Storage settings or Disk Cleanup, which is what Microsoft points you at. Both only offer you files that are safe to remove.

Deleting things out of the temp folder by hand is less tidy, because some files are in use and Windows will just skip them.

The Short Version

• Windows keeps at least five caches and they fix different problems.
• Browser cache for broken sites. Temp folder for space. Update cache for updates.
• Thumbnail cache for wrong pictures. DNS cache for one unreachable site.
• On this PC the five came to about two gigabytes in total.
• Two thirds of that was the temp folder, not the browser.
• There are two temp folders and they fill up very differently.
• Use Storage settings or Disk Cleanup rather than deleting files by hand.
• Clearing a cache never makes a PC faster. It makes it briefly slower.

Where to Next

Browser cookies are a separate thing from any of these caches, and clearing them costs you far more. It signs you out of nearly every site you use.

Work out your symptom first, then pick the matching cache from the list. That one decision saves you clearing four things that were never the problem.

Measure your temp folder first, with the line above. If it is large, that is where your space went and Storage settings will clear it safely.

If a single website will not load while everything else does, try `ipconfig /flushdns` on its own. One command, nothing else affected.

And if the real complaint is that the machine feels slow, no cache is your answer. Two numbers will tell you what is actually wrong.

If your temp folder turned out to be far bigger than mine, say the number in the comments. I suspect some of them are enormous.