Subdomains vs. Subdirectories and SEO

The question of subdomains versus subdirectories has been hotly debated for some time – and Google has attempted to clarify its stance even though it doesn’t always align with how SEOs view it.

In this article, I’ll review the two solutions, the debate, and which you should choose.

• What is a subdomain? 
• What is a subdirectory?
• The subdomain vs. subdirectory debate
• Local city pages
• Migrating a subdomain to subdirectory
• So: subdomain or subdirectory? 
• FAQ: What are the factors to consider when deciding between a subdomain and subdirectory for organizing website content?

What Is a Subdomain?

A subdomain is a dependent domain set up within the main domain (also known as the root domain).

For example, say your website’s root domain is acme.com, and you have a subdomain for the blog – that would look like blog.acme.com.

People use subdomains for things like blogs, country-specific locations, or any time it feels like there are substantial resources on a topic, and they don’t want to build out the main site.

One example would be a help center like support.google.com.

In all cases, subdomains help to organize the content by theme.

What Is a Subdirectory?

A subdirectory is a folder within your root domain that organizes your webpages. Subdirectories also organize content by silos.

For example, if your root domain is acme.com, you might have a subdirectory for the blog that would look like acme.com/blog and a subdirectory for your products that might look like acme.com/widgets.

This keeps the blog content in one place and the product content in another. Think about how you organize content on your PC hard drive – in hierarchy structures called directories or folders.

For SEO purposes, how you organize the content on your website in its subdirectories can make or break your SEO. At Bruce Clay, we call this SEO siloing, a concept we invented many years ago.

The Subdomain vs. Subdirectory Debate

Both a subdomain and a subdirectory nicely organize content by theme. So what’s the big deal?

Subdomains and subdirectories can both rank in the search results equally well, with the right content, all else being equal. However, if you want your main domain to benefit from the content on your subdomain, that may not happen.

Despite the fact that Google has said it doesn’t matter which you choose – a subdomain or subdirectory – subdomains are treated as entirely separate sites and you even verify them separately in Google Search Console.

In a 2017 Google Search Central video, Google’s John Mueller tried to settle the question of subdomains or subdirectories:

Watching that video, someone without a lot of SEO wisdom might think that it doesn’t matter either way.

What I see is a vague answer that doesn’t really touch on the intricacies of choosing a subdomain versus a subdirectory.

This video, in fact, lead to a heated debate between SEOs and Google reps on Google’s official advice, and here is just one snippet of that debate:

C’mon man. All respect but a year ago, you would have said “well, that’s not clear at all, nor does it even address the real question.”

— Rand Fishkin (@randfish) January 23, 2018

In 2018, Mueller again answered the question of how Google treats subdomains and subdirectories:

Here, Mueller says that “in general, we see these the same.” But he follows up with advice that people should try to keep the content on the main domain when possible and “use subdomains where things are really kind of slightly different.”

(Read: If you have topical themes that vary from the main domain and wouldn’t be appropriate there.)

For instance, say you have a brand that sells peanut butter and jelly. It would make sense to include these products on one domain using directories … peanut butter and spark plugs, on the other hand – opt for a subdomain.

This is more in line with the way many SEO experts view subdomains versus subdirectories because the data has shown in many common scenarios that subfolders make more sense from an SEO perspective.

Where we see arguments is around the concept of “equal.” Subdomains have long been used as microsites, meaning they have slightly tweaked content from the main site and perhaps have little redeeming quality. We believe that almost equal is not close enough.

Wanting to better understand Google’s perspective on subdomains, Will Critchlow interviewed Mueller at SearchLove and confirmed that Google sometimes does treat subdomains differently.

In that interview, Mueller said:

… we try to figure out what belongs to this website, and sometimes that can include sub-domains, sometimes that doesn’t include sub-domains.

Sometimes that includes sub-directories, and sometimes that doesn’t include specific sub-directories.

So, that’s probably where that is coming from where in that specific situation we say, “Well, for this site, it doesn’t include that sub-domain, because it looks like that sub-domain is actually something separate.”

So, if you fold those together then it might be a different model in the end, whereas for lots of other sites, we might say, “Well, there are lots of sub-domains here, so therefore all of these sub-domains are part of the main website and maybe we should treat them all as the same thing.”

And in that case, if you move things around within that site, essentially from a sub-domain to a sub-directory, you’re not gonna see a lot of changes. So, that’s probably where a lot of these differences are coming from. And in the long run, if you have a sub-domain that we see as a part of your website, then that’s kind of the same thing as a sub-directory.

In other words, there are situations where Google views subdomains as part of the main domain and other times when they don’t.

In some cases, there are massive benefits to moving the content from a subdomain to a subdirectory, and other times, there may not be.

How trusting are you that Google will get it right?

Local City Pages

As a side note, Mueller has also implied that in the emerging era of hyper-local, city information is best placed into a subdirectory. And many years ago, Matt Cutts (remember him?) told me that Google prefers subdirectories.

Migrating a Subdomain to a Subdirectory

If you want your main domain to benefit from the content on your root domain, then ultimately, you can migrate the content into subdirectories when it’s reasonable to do so.

In our experience, we’ve seen a traffic lift of sometimes 50% or more when people migrate from a subdomain to a subdirectory.

However, it has to make sense. Deciding on a subdomain versus a subdirectory needs an SEO expert’s opinion. In general, to make it work, the theme of the subdomain would have to be relevant to the main domain. And you’d have to weigh the cost-benefit of migrating the content, too.

Google’s Mueller commented on this topic in a 2022 video:

Mueller points out that when moving the content from a subdomain to a main domain, Google will re-evaluate the website:

I think one of the aspects here that is important when you’re moving from a subdomain to the main domain to a different directory, for example, is that we need to look at the new website overall and reevaluate the overall situation.

He goes on to say that “if you move from one domain to a different domain, then it’s easy for our systems to say, take everything here and just copy it over here. But if you move from a subdomain to a sub-domain within the main domain, you’re essentially merging different websites into parts of the target website. And that final outcome that you have will depend on your final structure.”

What he is referring to is that if you migrate the content on a subdomain to a main domain, you risk diluting the theme and/or not moving the content over correctly. And that can be a real problem for the main domain.

Let’s say you had a root domain about peanut butter and two subdomains about jelly and chocolate.

Migrating the content from the subdomains to the main domain would work just fine because the theme is still intact. You would still need to make sure you properly siloed the content on the main domain.

But if your subdomains were about something totally unrelated, you wouldn’t want to dilute the theme of your main domain.

So: Subdomain or Subdirectory?

The answer here is, unfortunately not cut and dry.

Ninety percent of the time, you will want to organize the content into subdirectories on your website when the content is related to the theme of the main domain.

However, there are situations when a subdomain makes the most sense. Large brands (like Google and others) can get away with having subdomains and potentially still prosper on the SEO front.

Because subdomains from big brands can have a ton of content, they have the ability to rank well in the search engines.

However, most websites need a lot of subject-relevant content to compete in the search results, and because most sites struggle with this, it is usually the best case to put all that great content on the main domain.

My advice? Stick to subdirectories. If confused, seek expert help.

Our SEO experts can help you make sense of subdomains, subdirectories, or anything else your SEO campaign is having trouble with. Schedule a FREE 1:1 consultation today.

FAQ: What are the factors to consider when deciding between a subdomain and subdirectory for organizing website content?

One key decision often arises: should you organize your content using subdomains or subdirectories? The answer depends on various factors which can significantly impact your website’s performance and user experience. Let’s explore the essential considerations.

Website Purpose

Before selecting your subdomain name, carefully consider its purpose and purpose of use. Subdomains may prove particularly useful if each stands as its independent entity – for instance if your blog resides under its subdomain name. However, a subdirectory is often more suitable if the content is closely related and an integral part of the main website.

SEO Implications

Search engine optimization (SEO) is a crucial aspect to contemplate. Subdirectories tend to benefit from the existing authority of the main domain, which can improve search engine rankings. Conversely, subdomains may be treated as separate entities, potentially requiring more SEO efforts.

User Experience

Consider the user experience. Subdirectories provide a seamless navigation experience, as they are perceived as part of the main website. Subdomains may create a disconnected feeling for users, requiring extra effort to access related content.

Maintenance and Management

Think about the ease of maintenance and management. Subdirectories are often more straightforward to oversee as they are part of the main domain’s infrastructure. Subdomains can introduce added complexity and require separate hosting and management.

Branding and Trust

Assess the impact on branding and trust. Subdirectories enhance the brand’s cohesiveness and trustworthiness as all content resides under the same domain. Subdomains can be used strategically to develop sub-brands or indicate specialized content.

The choice between subdomains and subdirectories should align with your website’s specific goals and user expectations. SEO considerations, user experience, management, and branding are pivotal in this decision-making process. You can select the most appropriate structure to enhance your website’s overall performance by carefully evaluating these factors.

Step-by-Step Procedure

1. Define your site’s purpose.
2. Evaluate the content to decide if it should be a separate entity or part of the leading site.
3. Consider the SEO implications of using subdomains or subdirectories.
4. Consider the user experience and how content organization impacts navigation.
5. Assess the ease of maintenance and management for your chosen structure.
6. Examine the impact on branding and trust that your decision will have.
7. Weigh these factors against your website’s goals and user expectations.
8. Make an informed choice based on evaluating the above considerations.

Bruce Clay is founder and president of Bruce Clay Inc., a global digital marketing firm providing search engine optimization, pay-per-click, social media marketing, SEO-friendly web architecture, and SEO tools and education. Connect with him on LinkedIn or through the BruceClay.com website.

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