What’s a browser cache? How do I clear it? Why would I want to?

Clear your browser's cache" is the first response that tech people often give if you encounter web page problems. We'll look at why that is and how to clear the cache.

The browser cache comes up in more of my answers than questions, but when I recommend it, the direction probably causes even more questions. Even when following instructions to empty the cache, many people aren’t clear on what this piece of magic really is and why clearing the cache would do anything at all.

Let’s review the browser cache, what it is, and why it exists. Along the way, we’ll review the steps to clear it in Internet Explorer, Firefox, and Chrome, and try to dream up some reasons why that sometimes helps.


What’s a browser cache?
The browser cache exists because of a basic assumption made by the folks who design browsers: the internet is slow. Perhaps more correctly, your internet connection is slower than your computer.

What that means is that it’s faster to get something to display from your hard disk than it is to get it by downloading it from the internet. Even with today’s faster internet speeds, that still holds very true.

When current browsers were designed, people noticed that many web pages contained the same elements and many sites had these all over their pages. For example, if you look at this page, you’ll see a logo at the top. It’s actually at the top of every page on this site. So the thinking was why download the same logo for every page? Why not just download it once and then keep it so we can use it again?

The cache is nothing more than a place on your hard disk where the browser keeps things that it downloaded in case they’re needed again. For instance, when you first visit a page on this site, the browser will download the logo so that it can be shown. Every time that you visit a different page on the site, the logo doesn’t need to be downloaded again; as long as the same logo is displayed, it’s already here.

The cache has a limit of how big it can get and you can usually configure how much space to set aside for it. Essentially, when the cache gets full, the items in it that haven’t been used in a while are discarded to make room for whatever new items you’re looking at now.


There’s a little more to it than that. For example, there are ways for me to update the logo on my site and have that override whatever is in your cache so what you see is always up-to-date. But by and large, that’s all it is: a place to keep things locally so that you don’t always have to download the same things all over again.

And it’s all transparent to you.

Until something breaks, of course.

And that’s where “clearing the cache” comes in.

For reasons that I simply can’t explain – other than by saying “stuff happens” – the cache can sometimes get confused. This seems to happen to most browsers and at random times. What you’ll see are partially loaded or badly formatted web pages, incomplete pictures, or in some cases, the wrong picture in the wrong place.

It’s not always a caching problem, but because it happens often enough, “clear your browser cache” is often one of the first diagnostic steps that you’ll hear from people like me.

Here’s how.

Clearing Internet Explorer’s cache
Examples are Internet Explorer 11; older versions are similar.

Click the Tools menu or click the gear icon in the upper right of the Internet Explorer window, then the Internet Options menu item. In the resulting dialog box, under Browsing History, click the Delete… button.
In the resulting Delete Browsing History dialog, it’s the Temporary Internet files and website files item that specifically refers to the browser cache. You can select or deselect other items as you see fit.

Once you’ve done so, click the Delete button.
Your browser cache is now empty.
Here’s a short video walking through the steps for Internet Explorer:

Clearing FireFox’s cache
Examples are version 25.0.1. Older versions are similar, although some of the specific options have changed.

Click the Tools menu (you may need to press the ALT key to make it appear) and click the Privacy tab.
Click the Clear your recent history link in the middle of the dialog.
In the resulting dialog, ensure that the Cache item is checked and that Everything is selected in the Time range to clear drop-down menu.

You can check other items to be cleared at the same time.

Click Clear Now.

Your browser cache is now empty.

Here’s a short video walking through the steps for Firefox:

Clearing Chrome’s cache
Examples are using Chrome version 31.0. Previous versions will be similar.

Click the menu icon at the top right of Chrome and then click History1
On the resulting page, click on Clear browsing data…
Then in the resulting dialog ensure that “Empty the cache” is selected (others are optional, but we’ll focus on only the cache.
Do also make sure that the Obliterate the following items from: drop-down menu is set to The beginning of time to clear the entire cache.

Click Clear browsing data.

Your browser cache is now empty.

Here’s a short video walking through the steps for Google Chrome:

An empty cache
Your browser cache is empty – so what?

An empty cache means there’s no confusion. As you visit web pages hereafter, the browser will download fresh copies of everything that you see on each page. Effectively, you’ve simply forced your browser to rebuild its cache from scratch as it loads or re-loads web pages. Any cache-related issues should be cleared up.