What cache is and why you might clear it

Cache is temporary data that your iMac stores to make programs run faster. When you visit a website, your browser saves images and files so it doesn't have to download them again. When you use an app, it stores information about your settings and recent actions. Over time, this cache can grow large and sometimes cause problems — a program might load outdated information, or your iMac might run slower because the cache is taking up disk space.

Clearing cache won't hurt your iMac or delete anything important. The worst that happens is a program takes a few extra seconds to load the next time you use it, because it has to rebuild the cache from scratch. Most people clear cache when a program is acting strange, when they want to free up storage space, or when they're concerned about privacy.

Key Takeaways

  • Browser cache lives inside Safari, Chrome, Firefox, or Edge — each one stores its own separate cache that you clear through that app's settings.
  • System cache is stored in hidden folders that you can access through Finder by pressing Command+Shift+Period, then navigating to Library > Caches.
  • Clearing cache for a single app is faster than clearing everything, and you can do it without restarting your iMac.
  • If a program keeps crashing or loading incorrectly, clearing its cache often fixes the problem without you losing any of your actual files or settings.

Clear cache in Safari

Open Safari and click Safari in the menu bar at the top of your screen. Select Clear History from the dropdown menu. A window will appear asking you what time period to clear — choose All History to clear everything, or pick a specific range like Last Hour or Today. Make sure the checkbox next to Cookies and other website data is checked, then click Clear History.

Safari will clear your browsing history, cookies, and cached website files all at once. This usually takes a few seconds. When it's done, the window closes and you're back to your normal Safari window. The next time you visit a website, Safari will download fresh copies of images and files instead of using the old cached versions.

Clear cache in Chrome, Firefox, or Edge

Open whichever browser you use. In Chrome or Edge, press Command+Comma to open Settings, then click Privacy and Security on the left side. Click Clear Browsing Data. In Firefox, press Command+Comma to open Preferences, click Privacy & Security, scroll down to Cookies and Site Data, and click Clear Data.

A window will appear with checkboxes for different types of data. Make sure Cached Images and Files is checked — you can leave the other boxes checked too, or uncheck them if you want to keep your browsing history. At the top, choose the time range: All Time clears everything, while Last Hour or Last Day clears only recent cache. Click the button to clear (it says Clear Data in Firefox, Clear Data in Edge, or Clear Data in Chrome).

Clear cache for a specific app

If one app is running slowly or acting strange, you can clear just that app's cache without touching anything else. Open Finder and press Command+Shift+Period — this shows hidden files and folders. Click Library in the sidebar, then double-click the Caches folder. You'll see a long list of folders, each named after an app or company.

Find the folder for the app you want to clear. For example, if Spotify is slow, look for a folder that starts with "com.spotify". You can also type the app's name into the search box at the top right of the Finder window to find it faster. Drag that folder to the Trash, then empty the Trash. The next time you open that app, it will rebuild its cache from scratch.

If you're not sure which folder belongs to which app, you can look at the date each folder was last modified — the most recently modified folders usually belong to apps you use often. When in doubt, don't delete a folder unless you're certain what it is.

Clear system cache and temporary files

Your iMac also stores temporary files and system cache in a few standard locations. Open Finder, press Command+Shift+Period to show hidden files, and click Library in the sidebar. You'll see several folders — the ones that hold cache are Caches, Logs, and sometimes Application Support.

The Caches folder is safe to clear entirely — it only holds temporary data that your iMac will rebuild as you use it. The Logs folder contains records of what your apps have done, and clearing it won't hurt anything. The Application Support folder sometimes holds cache, but it also holds settings and data you might want to keep, so be more careful there — only delete folders you recognize and are sure about.

To clear any of these folders, open it, select the files or subfolders inside, and drag them to the Trash. You don't need to restart your iMac. Empty the Trash when you're done, and the space will be freed up.

When to restart your iMac after clearing cache

You don't have to restart your iMac after clearing cache in most cases. If you cleared browser cache, just close and reopen your browser. If you cleared an app's cache, close and reopen that app. The cache will rebuild the next time you use it.

The only time a restart helps is if you cleared a lot of system cache and an app is still acting strange afterward. Restarting gives your iMac a fresh start and forces all apps to rebuild their cache from the beginning. But this is rarely necessary — clearing cache usually fixes the problem right away.

Frequently Asked Questions

Will clearing cache delete my passwords or saved information?

No. Cache is only temporary data. Your passwords, bookmarks, and saved form information are stored separately and won't be affected. If you want to keep that data, make sure the checkbox for "Cookies and other website data" is unchecked when you clear cache — though unchecking it means you'll have to log into websites again.

How much storage space does cache usually take up?

It varies widely depending on how much you browse and which apps you use. Browser cache can range from a few hundred megabytes to several gigabytes. System cache is usually smaller, but can add up over months or years. If your iMac is running low on storage, clearing cache might free up anywhere from one to five gigabytes, though it could be more.

Can I clear cache automatically on a schedule?

Most browsers have a setting to clear cache when you close them. In Safari, go to Safari > Settings, click the General tab, and check "Remove history items" — then choose how often (daily, weekly, or monthly). Chrome and Firefox have similar options in their Settings under Privacy. For system cache, there's no built-in automatic clearing, but you can use third-party apps designed for this purpose.

What if clearing cache doesn't fix the problem?

If an app is still crashing or running slowly after you clear its cache, the problem might be something else — try restarting the app, restarting your iMac, or checking if there's an update available. If the problem is with a website in your browser, try opening it in a different browser to see if the problem follows it or stays in the first browser.