What’s the optimal number of WordPress categories?

Up until WordPress 2.5, there was no built-in support for tags. This led to very long category lists because people were using it to define micro-details. Tags were added to improve the usability of your site. Having that said, we believe there is no specific optimal number of categories. The optimal number varies based on the complexity of your site. However, for the sake of structure and usability, it is best that you utilize sub-categories and tags.

Categories are meant to encompass a group of posts. It is always best to start with generic categories and work your way down with subcategories as your site grows. After having run multiple blogs, we have leared that blogs evolve. There is no way that you can come up with all the right categories. Chances are when starting out, you are only writing one post a day. Or maybe 3-5 posts a day. Having 30 top categories is pointless specially when some of them will only have one or two posts. You are better off with 5 generic categories that have fresh content rather than 30 top categories where the majority are not updated.

Let’s take a look at an example. Say that we are starting a social media blog in 2012. We want to share how-to tutorials, news, tools, case studies etc. We can create top categories like Twitter, Facebook, Google+, LinkedIn etc. As sub categories of each, we can have tools, how-to’s, case studies, news etc. However that is a very short-term mindset, and we will run into issues in the future. What if one of the social media network dies and a new one enters the game? You will be required to add yet another top level category and more sub-categories.

A much better way of structuring this social media blog would be to have top categories that are future-proof. You can have your categories like How-To’s, News, Case Studies, Tools, etc. But how would people know that it is about twitter? Well your categories are not suppose to do the entire job. This is where tags come in. Let’s say you wrote a how-to post about twitter, simply add the tag twitter. In your design just add a section called Popular Topics and control that manually with links to popular tags like Twitter, Facebook, Google+ etc.

When do you add Subcategories?

Let’s say that you do a case-study posts where sometimes you interviewed an expert for a specific case-study. Because there is no category called “expert interviews”, you will add that as a tag on that case-study post. If you find yourself doing a lot of interviews for case-studies and your expert interviews tag has 10+ posts in it and is consistently growing, then you should consider adding expert interviews as a sub-category of your main category “Case Studies”.

Yes, you will have to go back and edit your older posts. If your URL structure is /category/postname/, then you have make sure you are using the Redirection plugin. It automatically redirects your modified posts to their new URL, so you can keep all the search engine rankings.

Do I have to use sub-categories?

No ofcourse not. You can always leave popular tags as tags. In our example above, almost all posts will have a tag for a specific social media network like twitter, facebook, etc. But we are not creating those as categories. The only reason why you add sub-categories is to make it easy for your users to find the content. You are more than welcome to simply add the Expert Interviews tag in your site somewhere.

Remember the whole purpose of categories and tags are to make it easy for your users to browse your site.