A subdomain is an additional section of your domain name that comes before your main domain. For example, subdomain.maindomain.com.

You can add as many subdomains as you’d like, and each subdomain is treated as its own distinct domain (though not always for SEO – more on this in the post).

In this post, we’ll start off with a general discussion of subdomains and their SEO effect, as well as the pros and cons of using a subdomain.

Then, we’ll pivot from the “what” into the “how” and show you how to use a WordPress subdomain to create different WordPress installs on different subdomains. Or, you can also use one WordPress install to power multiple sites on subdomains.


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The SEO Impacts of Using a Subdomain

When it comes to the SEO impacts of using a subdomain, you’ll find people on both sides of the aisle.

Typically, the debate is between using a subfolder (yoursite.com/topic) and a subdomain (topic.yoursite.com).

For example, here at Kinsta, we use a subfolder for the Kinsta blog — “kinsta.com/blog“. However, you’ll find plenty of other successful businesses who opt to use a subdomain for their blog instead. For example, HubSpot uses “blog.hubspot.com”.

Some experts say that there’s little to no impact between the two approaches, while others say that you should try to avoid a subdomain in most cases as it can negatively affect SEO. According to John Mueller at Google:

“Google Web Search is fine with using either subdomains or subdirectories.”

He says it can take Google a little longer to figure out subdomains, but that in the long-term there’s no difference between the two and you should pick the one that works best for you. His only caution is that you should try to stick to your choice for the long-term, no matter which one you choose.

However, despite what Google says, there are a number of SEO case studies that point to subfolders being a superior approach for closely linked topics in most situations.

For example, Monster.co.uk saw a big jump in traffic after moving from a subdomain to a subfolder:

Monster.co.uk before/after moving blog to subdomain

Monster.co.uk before/after moving to subdomains

Of course, you’ll also find some case studies that go in the other direction and the HubSpot blog is a pretty good indicator that you can use a subdomain and still be successful.

In fact, this is such a divisive topic that John Mueller’s video above kicked off a whole debate on Twitter, which Search Engine Roundtable documented here.

So where does the truth lie? Unfortunately, we don’t have access to Google’s algorithm, so we can never really know for sure.

Google says it doesn’t matter, but most SEO experts seem to favor subfolders over subdomains when the content is closely related to the main domain name.

A good rule of thumb is that:

  • If the content is closely related to the root domain, use subfolders. For example, here at Kinsta, we use a subfolder for our blog (kinsta.com/blog) because it closely relates with the rest of the content on the Kinsta root domain.
  • If the content is fairly separate from the root domain, consider a subdomain. For example, we use my.kinsta.com as the URL for our customers’ hosting dashboards because these dashboards are private and not related to the frontend content on Kinsta’s site.

Pros and Cons of Using a Subdomain

To finish out the theory of using subdomains, let’s look at the pros and cons of using a subdomain:

Pros:

  • There’s no extra cost. You can create as many subdomains as you want without the need to purchase new domains.
  • Google says there’s no long-term difference between using subdomains and subfolders to separate your site’s content.
  • Subdomains make it easy to create separate WordPress installs that use the same root domain. While you can install WordPress in a subfolder, it makes it a little trickier because of the potential for URL conflicts.
  • You can launch multiple separate products from the same root domain, which helps you keep your branding. For example, music.amazon.com.

Cons:

  • Many SEO experts believe that subdomains are inferior to subfolders for SEO, especially if the content you’re planning to put on the subdomain relates closely to the root domain.
  • Even if Google treats subdomains equally, it can still take more effort to build links to that subdomain.
  • Because subdomains are separate domains, it can be harder to integrate them into the rest of your site. For example, if you’re using a single site WordPress install, you’d need two separate installs — one for your main domain name and one for the subdomain.
  • You’ll need to add each subdomain as a separate website property in Google Search Console.

How to Set Up a WordPress Subdomain Site

Now that you know a little more about the pros and cons of subdomains, let’s dig into how to apply subdomains to your WordPress site(s).

There are two main ways to set up a WordPress subdomain install. There’s no right or wrong, you’ll just want to choose the method that best meets your needs:

  1. Separate WordPress installs — with this approach, you’ll create a 100% separate WordPress install on a subdomain. For example, one WordPress install at yoursite.com and another WordPress install at sub.yoursite.com (or just one install on the subdomain).
  2. WordPress Multisite — with this approach, you can use one WordPress install to power one or more subdomain sites. For example, you could have yoursite.com, along with sub.yoursite.com and example.yoursite.com all running from the same WordPress install.

Here’s how to start working with both approaches:

How to Install WordPress on Subdomain

If you want to install WordPress on a subdomain, the process is generally the same as installing WordPress on your root domain — you’ll just need to first add your subdomain to your domain’s DNS or via your hosting dashboard.

If you’re hosting at Kinsta, you can add a subdomain by adding an A record or CNAME record in the Kinsta DNS area. Learn more about using DNS at Kinsta.

How to add a subdomain in Kinsta DNS

How to add a subdomain in Kinsta DNS

If you’re using a different host that uses cPanel, you can use cPanel‘s Subdomain tool to add a subdomain to any root domain that you’ve already added to cPanel:

How to add a subdomain in cPanel

How to add a subdomain in cPanel

Once you’ve configured your subdomain, you can install WordPress at that subdomain just like you would your root domain.

For example, if you’re hosting at Kinsta, you could use Kinsta’s Add Site tool to create a new site at that subdomain:

How to install WordPress on a subdomain at Kinsta

How to install WordPress on a subdomain at Kinsta

Or, if you’re hosting elsewhere, most WordPress autoinstaller tools also let you create a new WordPress install at a subdomain:

How to install WordPress on a subdomain with an autoinstaller

How to install WordPress on a subdomain with an autoinstaller

Finally, you could also just manually install WordPress at that subdomain.

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How to Set Up WordPress Multisite Subdomain Installs

With WordPress Multisite, you can create a network of WordPress sites that are all powered by the same WordPress install.

Your “main” WordPress install will be yoursite.com, and then you can give each network site its own subdomain like:

  • site1.yoursite.com
  • site2.yoursite.com
  • Etc.

When you install WordPress Multisite, you’ll get the option to choose between Sub-domains or Sub-directories during the setup process like this:

How to choose subdomains during WordPress Multisite install

How to choose subdomains during WordPress Multisite install

If you’re hosting at Kinsta, Kinsta’s Add Site tool lets you activate WordPress Multisite right away, and will also give you the option to select Subdomains:

The Kinsta Multisite installer tool

The Kinsta Multisite installer tool

In addition to choosing the subdomain option during the Multisite setup process, you’ll also need to create a wildcard subdomain entry. This entry is what lets you create new network sites and automatically direct traffic to the right site.

You can create a wildcard subdomain entry by adding an A record or CNAME record with an “*” (asterisk) to your domain’s DNS. For example, here’s how it looks at Kinsta:

How to add a wildcard subdomain

How to add a wildcard subdomain

For a much deeper look at how to configure WordPress Multisite, check out our full guide to setting up WordPress Multisite.

How to Move WordPress from Subdomain to Root

If you install WordPress on a subdomain and then want to move WordPress from the subdomain to your root domain at some point in the future, the process is the same as if you were migrating a WordPress site from one root domain to a completely separate root domain.

Again, a subdomain is essentially just a separate domain name. So moving from “sub.yoursite.com to anothersite.com” is the same as moving from “yoursite.com to anothersite.com“.

For a detailed look at how to do this, check out our full guide on how to change your WordPress domain.

Summary

A subdomain lets you create an additional domain name “below” your root domain.

Subdomains can be especially helpful when you want to add some separation between the content on a subdomain and that on the parent domain. For example, Kinsta puts its hosting dashboard at my.kinsta.com and Amazon separates its music service into music.amazon.com.

However, many SEO experts prefer subfolders in situations where the content is closely linked, like your blog.

If you want to use a subdomain with WordPress, you can either create entirely separate WordPress installs on each subdomain, or you can use a WordPress Multisite network to create separate sites on subdomains that are all powered by the same WordPress install.

Do you still have any questions about how to use subdomains with WordPress? Leave a comment and let us know!

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