How to clear the cache in Safari on Mac and iPhone - and what it does

Like every web browser, Safari stores data on your Mac, iPhone, and iPad, with the express purpose of speeding up your online life. You may have the kind of internet speed that Apple Park takes for granted, but even so, it's better to spend that speed where it's needed.

So when you revisit a website, Safari makes it so that as far as possible, you only need to download what has changed. Even with a news site that is being updated all day, the basic layout, the furniture of the page, doesn't change all that often, so Safari might as well download it once.

Behind the scenes, then, whenever you ask Safari to go to a site, it goes there with half an eye on what elements of the site it has already stored on your device. Then it will load up anything it can from your device, because retrieving locally stored data is always faster than downloading it.

No question, a Safari cache is a good thing. Except when it isn't.

When you should clear Safari's cache

It's possible for things to go wrong. If Safari doesn't appear to be loading a site, it could be that there's some data corruption in the cache.

Or it could be simply that you are tight on space and all of this invisibly stored cache data is taking up a lot of room. When you're particularly low on space, you know it, too, because your device runs noticeably slower.

So if you are having problems any time you're browsing the web on a Mac, iPhone, or iPad, clearing the cache is at the very least a good first troubleshooting step.

You don't want to inadvertently introduce new problems or inconveniences, though. And clearing caches could also remove passwords that you thought Safari was saving for you.

So before you empty the cache, make sure that Safari is saving those passwords. On the Mac, go to System Preferences, click on Apple ID, then iCloud.

Or on iOS, open Settings, tap on your name at the top, then iCloud.

In either case, then check that Safari is turned on. With the Mac, that means a tick box is on, and with iOS, it means the slider button is turned on and showing green.

How to clear the cache in Safari on Mac

1. Launch Safari
2. Click on the Safari menu at top left
3. Choose Preferences
4. Click on Advanced
5. Tick the Show Develop menu in menu bar to set it to on
6. Close the Preferences window, and open the Develop menu
7. Choose Empty Caches

There is no OK button, and then no visible confirmation that the caches have been cleared. But they have been.

How to clear the cache in Safari on iPhone and iPad

1. OpenSettings
2. Scroll down to Safari and tap
3. Choose Clear History and Website Data
4. Confirm by tapping the new Clear History and Data button that pops up

Unlike with the Mac, there is a visible indication that the cache has been cleared. The option for Clear History and Website Data is greyed out and unavailable.

Note that it won't stay unavailable. It is immediately available the moment you do anything more in Safari.

What happens next

Once you have cleared the cache, you will typically find that some site loading problems are resolved. You'll also find that your device runs faster.

Except, of course, the next time you browse to a website, it will load a little slower than you're used to. But that will speed up again - once Safari has once more cached the site.