Should I clear the cache on my Mac? Usually no, and here is when the answer is yes

What a cache is for, and why deleting it makes things slower

A cache is a copy of something that was expensive to produce, kept so it does not have to be produced again. Safari caches the images and scripts of sites you visit so the second visit loads from disk instead of the network. Spotlight caches an index of every file so a search takes a tenth of a second instead of scanning the disk. Photos caches thumbnails so scrolling through 20,000 pictures is smooth. The font system caches rendered glyphs, the Dock caches icons, apps cache their last window layout, the Mac App Store caches app metadata, and Xcode caches compiled code. Mail caches message headers so a mailbox opens instantly.

Every one of those is a trade: a few megabytes of disk for a few seconds, or minutes, of work avoided. Delete the cache and you do not get the work back; you get the work again. The first launch of every app re-renders, re-downloads, re-indexes. A Mac that has just had its caches wiped is measurably slower until they are rebuilt, which takes anywhere from an hour (browser) to a day (Spotlight, Photos). That is the opposite of what the person deleting them wanted.

It is also why the space does not stay freed. Caches grow back to roughly their previous size because the same apps do the same work. The long-standing Apple Community answer is still the whole story: caches should not be deleted under normal circumstances, and clearing them does nothing for performance.

The idea that clearing caches speeds up a Mac comes from two real things that have been misremembered. One is the browser cache in the dial-up era, when a bloated cache on a slow disk really could slow page loads. The other is that a specific app with a corrupted cache misbehaves, and deleting that one cache fixes it. That second case is real, and it is the whole legitimate use of cache clearing, so the next section is about doing it precisely.

Should I clear this cache? A one-minute decision

Walk through the steps in order. Most people exit at the first or second one.

The flow has no step for "to free space" or "to speed things up", on purpose. Neither works, and the free up space guide lists the places where the real gigabytes are.

Which caches are worth clearing, and when

Four cases, each with a specific trigger and a specific target.

• One app that misbehaves. It crashes on launch, shows an old version of its data, draws its window wrong, or hangs on the same screen every time. Quit it, open Finder, press Shift + Command + G, type ~/Library/Caches, find the folder named after the app or its developer (com.company.AppName), and move that one folder to the desktop. Relaunch the app. If it is fixed, delete the folder; if not, put it back. The app rebuilds its cache on first launch, which may be slow once.
• A browser showing stale pages. A site you updated still shows the old version, a login loop, a page that will not load while others do. Clear that site's data, not the whole history: Safari, Settings, Privacy, Manage Website Data, search for the site, Remove. In Chrome, click the icon left of the address, Site settings, Clear data. Clearing all browser data signs you out of everything and makes every site slower for a day; one site at a time has no side effects.
• Xcode DerivedData. On a developer's Mac this is routinely 20 to 100 GB and is pure build output. Xcode, Settings, Locations, click the arrow next to Derived Data to open it, and delete its contents with Xcode closed. The next build of each project is a full build, which takes minutes, and then it is back to normal. Old simulator runtimes and device support files in the same area are also fair game, from Xcode, Settings, Platforms.
• Huge single-app caches you can name. Docker's disk image, a video editor's render or proxy cache, Spotify's downloaded cache, Dropbox's .dropbox.cache folder, Google Photos Backup. Each has a setting or a button inside the app to clear it, which is the right way, because the app knows what it needs to keep.

In all four cases the common thread is that you know exactly which cache and exactly why. That is the difference between troubleshooting and tidying, and only the first one pays.

Which caches never to clear by hand

These show up in "clean your Mac" guides and are either protected, pointless, or actively harmful to touch.

• /System/Library/Caches and /Library/Caches. System and shared caches, owned by root. macOS manages them, rebuilds the important ones at startup, and the sealed system volume refuses most changes anyway. Guides that route round the protection with Terminal and sudo are describing how to produce a Mac that boots to a blank screen.
• Font caches. The old atsutil trick for clearing font caches dates from problems that macOS fixed years ago. Clearing them today means every app re-renders every glyph on next launch and gains nothing. If fonts are genuinely misbehaving, Font Book, File, Restore Standard Fonts, or a safe mode restart, is the supported route.
• Kernel and dyld caches. These make the Mac boot. Apple silicon Macs rebuild them only during updates and on a sealed volume. Do not go near them.
• Spotlight's index. Not technically a cache but treated like one by cleaners. Deleting it forces a full re-index that keeps mds_stores busy for hours and makes search useless meanwhile. Rebuild it only if search is actually broken, and do it from System Settings, Siri and Spotlight, Spotlight Privacy, by adding and removing the disk.
• Photos, Mail, Messages and Notes caches inside their containers. They sit next to the databases those apps depend on. The apps rebuild thumbnails and previews themselves; a wrong click in the same folder deletes the library.
• ~/Library/Caches as a whole. Nothing in it is dangerous to delete, which is why guides recommend it, but nothing in it is useful to delete either. It is a few gigabytes, it regrows in days, and the Mac is slower until it does.

If a Mac-wide cache problem is real (fonts rendering wrong everywhere, icons blank, menus misdrawn), the supported fix is a single restart in safe mode: hold Shift at startup on Intel, or on Apple silicon hold the power button, pick the startup disk, then hold Shift and choose Continue in Safe Mode. Safe mode clears the caches macOS knows are safe to clear, checks the disk, and boots without third-party extensions. Restart normally afterwards. Apple's own storage support page lists this as the way to clear certain system caches.

What happens if you delete ~/Library/Caches anyway

Plenty of people have, so the timeline is well known.

Immediately: the Storage pane shows a few gigabytes more free, typically 2 to 8 GB on a personal Mac, more if a single app had a huge cache (which was the only one worth deleting). First hour: every app you open takes longer to launch and longer to show its first screen. Safari re-downloads every site's assets. Mail re-fetches headers for every mailbox. Music and Photos redraw artwork and thumbnails one by one as you scroll. Some apps show a blank or default state once, then recover. A few, badly written ones, crash on first launch because they expected a folder to exist, and work on the second.

First day: Spotlight and Photos may do a partial re-index if their caches were in the folder, which is a warm Mac and a busy fan for a few hours. First week: the caches have grown back to about where they were. The space is gone. The Mac is now exactly as fast as it was before you started, having been slower in between. The Apple Community threads that start with a friend clearing someone's caches to make the Mac faster are the canonical example: it got slower.

Nothing permanent is lost, which is why this is on the "pointless" list rather than the "dangerous" one. The danger comes when the same guide adds "and ~/Library/Application Support" or "and Containers" to the list, because those hold the data, not the cache.

What cleaner apps do when they "clear cache"

Every Mac cleaner has a button that reports several gigabytes of "system junk" or "cache files" and offers to remove them. What it is counting is ~/Library/Caches, the browser caches, log files, and often the language files inside apps. The number is real and the deletion is real; it is also exactly the wholesale deletion described above, with the same outcome. The gigabytes come back, the Mac is slower until they do, and the cleaner reports the same number again next month, which is the business model.

Two things make cleaners worse than doing it by hand. They do not know which app's cache is safe to delete right now, so they delete caches belonging to running apps, which is how a cleaner produces a crashed app or a corrupted library. And their heuristics for "junk" are loose: the MacRumors thread quoted below describes one classifying a user's entire music collection as a Spotify cache. The Mac cleaner comparison measures what each one actually recovers versus the built-in Storage pane.

If you like the idea of a button, the honest version of it already exists in macOS: System Settings, General, Storage, Recommendations, and the Empty Trash Automatically switch. For a slow Mac, the answer is almost never a cache; it is a process using the CPU or memory right now, which the why is my Mac slow guide walks through, and which Safe to Quit shows in the menu bar as it happens.

How to clear one app's cache safely, step by step

The one procedure worth knowing, for the one case where it helps.

1. Confirm the app is the problem

   It should be misbehaving in a way that points at stale data: crashing on launch, showing old content, wrong layout, stuck on one screen. A slow Mac in general is not that; check Activity Monitor instead.

2. Quit the app completely

   Command + Q, or right-click its Dock icon and choose Quit. Check it is gone from the Dock. Deleting a cache while the app is running is the one way this procedure can go wrong.

3. Open the Caches folder

   In Finder press Shift + Command + G, type ~/Library/Caches and press Return. Sort by name. Find the folder named after the app or its developer, usually in the form com.developer.appname.

4. Move that folder to the desktop

   Move, do not delete. Only that one folder. If there are two or three with the same developer prefix, move those too.

5. Relaunch and test

   Open the app. First launch may be slower while it rebuilds. If the problem is gone, drag the folder on the desktop to the Trash. If the problem is still there, quit the app, move the folder back, and look elsewhere: the app's preferences, an update, or its support site.

6. For a website, clear only that site

   Safari: Settings, Privacy, Manage Website Data, search the site name, Remove. Chrome: click the icon left of the address bar, Site settings, Clear data. You will be signed out of that site and nothing else.