Understanding Subdomain vs. Subdirectory: Which Is Best for SEO?

In the SEO world, one of the biggest controversies is Subdomain vs. Subdirectory.

Which one works best for SEO? Does it really matter? If a blog is currently hosted on your subdomain, should you shift it into a subdirectory? What is Google’s stand on this?

These were just a couple of questions picked from the heaps of most commonly asked questions within the SEO community, which usually receive clashing responses.

But don’t worry, we have got your back.

In this blog, we will try and clear up this confusion and help put an end to this ongoing debate once and for all. We will go in-depth on this matter and basically look at:

• What Are Subdomain and Subdirectory?
• Where Does This Confusion Come From?
• What Is Google’s Take on Subdomain vs. Subdirectory?
• Subfolders: The Debate
• Subfolders: The Challenges
• Conclusion: Subdomain or Subdirectory – Which One Is Right for Me?

What Are Subdomain and Subdirectory?

Before we dive right into which one is better for SEO – subdomains or subdirectories, let us first go through the technical difference between both quickly.

For example, blog.yourdomain.com is a subdomain, while yourdomain.com/blog/ is a subdirectory.

Basically, think of subdomain (which is also called subfolder) as the offspring of the parent domain, and at times, they are used to host blogs, separate mobile websites, quote forms, eCommerce stores (when they’re part of a larger website, internationalization (separate sites to target separate markets), and so on.

Take a look at the subdirectory or subfolder example once again and see how the “/blog/” is seated within the main domain i.e., “yourdomain.com” indicating that it is part of the main site just like any other web page. Therefore, in essence, the subfolder is just another page on the website.

On the other hand, if you look at the subdomain, it is seated outside of the main domain. It lies within its own partition of yourdomain.com. In the given example, the site is using the subdomain to host a blog.

Simply put, when looking at a URL, the subdomain will always lie before the origin domain, while the subdirectory will always lie after it.

If you are not certain about the number of subdomains your website is using presently, or whether it is even using one at all, you can use one of the site auditing tools available in the market and check your website structure.

This brings us to our next topic. What is the reason behind this major “Subdomain vs. Subdirectory” debate within the SEO community? And when it comes to SEO ranking, is one better than the other? If yes, then which one?

Let’s dive in!

Where Does This Confusion Come From?

First of all, let’s straighten out one fact; your site’s structure substantially influences your organic search performance.

Choosing between a subdomain and a subfolder for specific areas of your website can actually boost or obstruct your capability to prompt growth. But likewise, there are some situations where hosting part of your website on a subdomain is only logical.

So this is somewhat an “it depends” situation. You must grasp the various usage scenarios and how they can significantly influence your website’s organic performance.

This brings us back to the original question once again – where does this confusion come from then?

This argument is triggered by the fact Google regards subdomains as separate units to the root domain, mostly because a few sites put distinct content on subdomains that should not really belong to the main website. And if truth be told, in some cases, people controlling the main domain are different from the people controlling the subdomain.

So going back to the example we discussed above:

• The subdomain blog.yourdomain.com is not regarded as part of your main domain i.e. yourdomain.com by Google.
• The subdirectory yourdomain.com/blog/ is regarded as part of your main domain yourdomain.com by Google.

This implies that the content, along with its valuable assets like backlinks, you are hosting on a subdomain, are not being considered by Google’s algorithm while ranking your main domain on the search results.

It is almost as if the content you have hosted on that subdomain is hosted on a completely separate domain for ranking objectives. And when we look at it in this way, it helps clear things up a little bit.

Even though it may not strike as being a good thing to some people, at times, it only sounds logical for subdomains to be treated as a different unit to the main domain, particularly when the subdomains are portraying a different business or sections.

While usually a subdomain is linked to the root domain, either through internal links or a navigation menu, sometimes it won’t be. This is an essential component when determining which path you should take when building your website or its new division.

What Is Google’s Take on Subdomain vs. Subdirectory?

This is certainly not about saying that subfolders are better for SEO and subdomains are not. It isn’t that straightforward.

Nevertheless, we must understand where the various recommendations come from and how they measure up to Google’s guidance.

Back in 2017, John Mueller, Senior Webmaster Trends Analyst at Google, discussed this subdomain vs. subdirectory confusion in a video and the advice has not changed since then.

He revealed that whether websites are using subdomains or subdirectories, Google is fine with either.

Subfolders: The Debate

The chances are that you are wondering that if Google itself says it’s fine with websites using either subdomains or subdirectories, what is the point of this debate after all?

In order to answer this question, we need to review two of the top three ranking factors of Google:

• Content
• Links

Simply because Google says that it is fine with websites using either subdomains or subfolders does not mean that there are no added advantages of using one over the other.

Or to paraphrase it:

Will Google penalize you if you host your website’s content on a subdomain? – Of course not.

But if instead, you placed that content on your main domain, could that content (along with its backlinks, if any) help your root domain rank higher and drive more traffic? – Definitely, yes.

Suppose your content and backlinks are divided between your main domain and a subdomain. In that case, both of these entities’ overall domain authority is going to be lower compared to if everything was placed on the main domain using subfolders instead.

This is the reason people commonly notice a boost in their overall organic search visibility as well as traffic inflow (in comparison to the two seen individually) when they shift relevant subdomains into subdirectories on the root domain.

You will come across heaps of success stories of site owners bagging substantial gains after migrating their content from a subdomain to a subdirectory on their main domain if you look around.

Twitter is a great platform to check out such stories as many people love sharing their experiences regularly over there.

Let us not forget the fact that all along we have been talking about shifting blog content from subdomains to subfolders. Now by default, those blogs are generally content-rich (typically, most businesses host their best content on their blog) and therefore it is quite common for that blog to earn backlinks. Therefore, here the subdomain has topical relevance as well as DA that is closely aligned to the primary domain.

Here, the subfolder is acquiring the relevance and authority (from content and backlinks) during the shift of content, if truth be told. When this inherited authority is joined with the primary domain’s existing authority, as a result, there is a boost in the site’s overall authority as well as organic search visibility which becomes larger than when the two were viewed as individual entities earlier.

Typically, good content that is scoring good backlinks will pretty much always promote improved SEO results when migrated from a subdomain to a subfolder.

Subfolders: The Challenges

In the perfect universe, you’d have complete control over whether to use subdomains or subfolders for different areas of your website.

Nevertheless, in reality, things are not often that straightforward and commonly, you will be required to make some compromises now and then depending on technical limitations including:

• Inability to set up international websites in subdirectories
• Developers not willing to host a blog on the same web server as an eCommerce store
• A wish to have a dedicated blogging platform instead of an in-built blog of an eCommerce platform
• Other features such as quote form not being able to be placed on the same server as the primary domain because of being written in different coding languages

These were just a few examples of the challenges or limitations you can face while deciding whether to use a subdomain or subdirectory in various areas of your website.

For example, Shopify pushes people to utilize subdomains for international stores (i.e. us.yourdomain.com instead of yourdomain.com/us/), and here using subfolders is not a possibility, whatsoever the advantages may be.

Likewise, if you want to use a WordPress blog and your website runs on a content management system that does not support doing so on the same server (or provides you the access for the same). In that case, your developer will ideally recommend you to use a subdomain for comfort. However, sometimes it is possible to use a reverse proxy in this situation.

Conclusion: Subdomain or Subdirectory – Which One Is Right for Me?

Despite all this, one thing that can be said for sure is that a great deal of confusion still continues to surround this topic – whether or not subdomains can hurt your SEO efforts.

There are still lots of disagreements on whether Google regards these two any differently or not.

By and large, amid all these arguments, the SEO community does settle with hosting content in a subfolder instead of a subdomain provided that there are no technical limitations or legal restrictions in various countries.

Having said that, it is also crucial for you to take the context of this agreement into account and think about what you are considering to host on a subdomain.

If you are considering hosting an eCommerce store or blog, then you should always prefer to host this content on a subfolder.

However, if it is a quote form or content that is not probable to add any value to your website or contribute to its SEO results, from either topical relevance or authority viewpoint, do not just select subfolders by default.

Suppose you do find a reason to use a subdomain. In that case, you should never overlook it, and features such as quote forms and even support centers (typically behind the login screen) will not hurt the SEO potential of your website, if hosted on a subdomain instead of a subdirectory. If truth be told, you will most probably observe no difference using subfolders in these situations.

Most of the time, a subfolder is often preferred over a subdomain from an SEO point of view. But there are things that you need to consider prior to making any final decisions.

When it comes to hosting content like your blog, it is a relatively easy decision to make. But when it comes to hosting other types of content and site features, you need to think about several considerations and weigh the pros and cons of both the options as it isn’t an easy decision always.

Just make sure that you properly understand how and to what extent your decision can influence your website’s overall SEO performance. Be sure to bring these explanations to the table when discussing which road you should go down with developers and stakeholders.