Subdomains vs. Subdirectories – What Should I Know About Subdomains and SEO?

Posted March 23, 2011 by Team UpCity | 7 comments

This post is meant to be helpful for those with an intermediate level understanding of SEO. If you have a basic understanding of how Google and other search engines rank pages and are aware of some basic SEO best practices but aren’t yet an SEO expert, we think you’ll find this post useful. You can also find DIYSEO posts classified by level of expertise on the following pages:

• Posts for any SEO experience level
• Posts for beginner level SEO (those new to SEO)
• Posts for those with an intermediate level of SEO understanding
• Posts for those with an advanced level of SEO understanding

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One SEO question we’re frequently asked is where to have new sections of a site “live”. For instance you might be adding a forum so that you can better serve your customers and people looking to learn more about your company. Since there will be a lot of useful content there about your product and your niche, you want to have all of the posts that your staff and your customers and potential prospects make show up in search engines. You’re presented with three potential options:

• Use a third party solution and have the forum live on their site. This might make things pretty turnkey and easier for you. To get to the forum, people would type in the URL forum.notyoursite.com.
• Have the forum live on a subdomain of your site – this means that the forum will live on a special section of your domain. The URL would look like forum.yourwebsite.com.
• Have the forum live in a subdirectory of your site – this means that the forum will live off of the main section of your domain. The URL would look like yoursite.com/forum

So what’s the best place to “put” your forum for SEO?

The answer is generally (but not always) a subdirectory. The reason for this is that often times the forum content people are creating for you will attract links. Content that gets links helps tell Google that that entire site is trustworthy. If you host your content on another site then any links you get are telling Google that their site is trusted, so that option isn’t ideal.

Towards the same end, a subdirectory is generally acknowledged to generate more trust or “link equity” for your main domain than a subdomain. This is a similar premise: by putting your forum on the root domain you’re telling the search engine that this content is closely aligned with your main domain, and in turn the engines generally assign slightly higher weight to the transfer of equity from a subdirectory to the main domain than to the transfer of equity from a subdomain to the main domain.

This said, if you have specific reasons for your business to choose one of these options over another, you might want to opt for a less SEO friendly option. If you’re trying to determine what the difference between the tactics you can use the following mental model as a way to “grade” the options from an SEO perspective (NOTE: this is a very rough estimate meant to be directionally useful):

• Other Domain: 50
• Subdomain: 90
• Subdirectory: 100

So choose the option that has the best combination of SEO and general business benefit for you.

Categories: SEO Questions