Subdomain vs. Subdirectory: What They Are & Which Is Better for SEO

Whether to use a subdomain vs. subdirectory model is a long-standing debate in the SEO community.

In this post, we’ll review these two options. And provide a verdict on which is better for SEO.

Let’s start.

What Is a Subdomain?

A subdomain is an extended part of your domain name that’s built for a specific purpose. And acts as a separate site.

For example, you can create a subdomain like blog.yoursite.com to host your blog content.

Another reason why you might use a subdomain is to separate the ecommerce portion of your website from its main domain.

By introducing a subdomain like shop.yoursite.com.

This helps you to create a different look, feel, and functionality for your online store than your main website. 

You’ll come across subdomains like these all over the internet. They’re incredibly common.

To see whether your site is using any subdomains, crawl your website with Semrush’s Site Audit tool.

Follow the Site Audit configuration guide to set up your project.

Then, go to the “Crawled Pages” tab and click “Site Structure.”

You’ll see a list of subdomains on your site.

But does having subdomains harm your SEO?

Let’s find out.

The Traditional View on How Subdomains Affect SEO

Many SEOs argue that content hosted on subdomains doesn’t rank well on Google.

Here’s their reasoning:

Subdomains may not fully benefit from the backlinks (links from other sites that point to yours) the main domain has garnered over the years.

Google treats subdomains as distinct websites. Which means they crawl and index subdomains separately.

As a result, you may have to work on gaining backlinks for each subdomain separately to improve their rankings. Which requires a lot of time and effort.

Without that added effort, content on those subdomains may not rank as well as it could’ve if it were hosted on subdirectories instead. (You’ll hear more on subdirectories later in this guide.)

Also, the more subdomains you have, the harder it can be to maintain your website overall.

You may end up with duplicate content (content that’s identical to content found elsewhere) and/or improper interlinking (links to other pages on the same website) between the main domain and its subdomains.

These errors can hurt your website rankings and the user experience.

Plus, collecting and analyzing data for SEO reports can be more difficult when you’re dealing with multiple subdomains. Because it may require additional tools or settings to merge data effectively.

For all these reasons, SEOs usually recommend using subdirectories instead of subdomains.

What Is a Subdirectory?

A subdirectory (also called a subfolder) is a folder located within the main domain. It clearly falls under your domain name.

Similar to subdomains, subdirectories help you organize your website content into different categories or sections.

For example, you can create a subdirectory like yoursite.com/blog to host your blog content.

If you’ve crawled your website with the Site Audit tool, you can find all subdirectories you’re using.

Just navigate to the “Crawled Pages” tab and click on “Site Structure.”

You’ll see a list of subdirectories on your site.

But what difference do subdirectories make to SEO?

Let’s find out.

The Traditional View on How Subdirectories Affect SEO

Many SEOs believe that subdirectories are more SEO-friendly compared to subdomains.

Here’s why:

While Google often views subdomains as separate entities, subdirectories are seen as part of the main domain.

This means that all the hard work you put into building backlinks is more likely to benefit every piece of content under that main domain, including those in subdirectories.

That’s because the link equity usually gets distributed throughout the domain.

Another upside of using subdirectories is that they allow for simplified management.

Because everything sits tidily under one domain umbrella, there are fewer technical headaches.

For example, you wouldn’t have to worry about setting up and maintaining separate hosting.

And you can easily create new subdirectories for different sections of your website, such as your blog, your news section, etc.

Doing this on subdomains would require more effort and resources.

Better yet, tracking website data is more straightforward with subdirectories. Because you can easily get a holistic view of your site’s performance in one place.

These benefits are why SEOs often insist on using subdirectories.

Exploring the Subdomain vs. Subdirectory Debate

The topic of subdomain vs. subdirectory is hotly debated in the search community.

We’ve heard the SEOs’ side of the argument.

To recap:

One major reason why they dislike subdomains is because they believe Google views subdomains as separate entities—not as part of the same website. So, the content hosted on them might not benefit from the main domain’s accumulated domain authority.

But what does Google think of this?

Google’s John Muller once said that it’s fine to use either subdomains or subdirectories.

Google web search is fine with using either subdomains or subdirectories.
 

– John Mueller, Google

Suggesting it doesn’t make any difference from a ranking standpoint. Positively or negatively.

Keep in mind that Google has evolved its understanding of domain structures over the years. 

This means that while they may treat subdomains as separate entities, they can still identify and acknowledge the relationship between the main domain and its subdomains.

And with proper internal linking, you can make it clear that your subdomains belong to the same website.

Internal linking facilitates bots’ abilities to crawl all the pages on your site (including those on subdomains). And helps distribute link equity among them.

Which puts an end to the myth that subdomains are bad for SEO.

As long as you use them correctly, subdomains are fine for your SEO performance.

Should You Use a Subdomain or a Subdirectory?

From an SEO perspective, it’s OK to use either option. They’re equally good for SEO, according to Google.

But there are other reasons to choose a subdomain over a subdirectory. And vice-versa.

When You Should Use a Subdomain

Using a subdomain can be beneficial in several scenarios.

Here’re some situations when implementing a subdomain might be the right choice:

1. You Company Operates Internationally

If your business operates in multiple countries and you want to offer content tailored to each location, subdomains can be a great solution.

For example, we use subdomains like es.semrush.com and fr.semrush.com to cater to different regions.

This way, we offer a more relevant and personalized experience to our global audience.

2. You Need to Do Testing

Subdomains are often used for staging environments. To test new features, updates, or designs before rolling them out to the main site.

For this, developers might create a subdomain like dev.example.com or staging.example.com.

This will help them spot and fix any issues before going live. And ensure that users have a seamless experience.

3. You Want to Implement Distinct Design and Functionality

If a part of your website requires a very different design and functionality from your main site, a subdomain can provide the necessary distinction.

For example, you might use a subdomain to distinguish the ecommerce part of your website from the main domain.

A subdomain would look something like shop.example.com, while the main domain would be example.com.

Google does this for their own online shop:

This way, you can introduce a new design and functionality for your ecommerce store without affecting the site.

When You Should Use a Subdirectory

Here’s when implementing a subdirectory might be more beneficial:

1. You Need Something Easy to Manage

If you want to simplify website setup and maintenance, subdirectories are a good option. 

Subdirectories don’t require additional technical configurations the way subdomains do.

You don’t need to set up a new hosting account, SSL certificate, or analytics tracking for the subdirectory.

Plus, you can easily create and edit subdirectories within your main website’s content management system (CMS).

This streamlined approach not only makes the initial setup quicker and more straightforward, but also reduces the ongoing administrative work.

2. You’re Prioritizing Consistent Branding

Subdirectories can help you maintain a consistent branding and user experience across your website.

Subdirectories share the same design elements as your main website. Which can create a unified and coherent impression for your visitors.

Which is what the American Lung Association has done:

But subdomains can create confusion. Because they may have different design elements than your main website.

This inconsistency can lead visitors to second-guess the subdomain’s authenticity.

Optimize Your Subdomains & Subdirectories for SEO

The choice between subdomains and subdirectories largely depends on reasons outside of SEO.

Both can be SEO-friendly.

Whether you decide to use subdomains or subdirectories, you need to optimize them for the best chance of ranking in search engines.

This means targeting the right keywords, doing on-page SEO, building backlinks, and avoiding technical SEO issues.

Semrush has a suite of SEO tools that help with all of the above and more.

Sign up today to get started.