Which Is Better for SEO? – Sub Domains vs Sub Directories

SEO: Distinguish the benefits between sub domains & sub directory

The URLs and the ease in which a site navigates are essential for SEO but the components of site structure don’t stop just yet. Take sub domains and sub directories for instance. These are examples of a site’s structural component that play an essential role in how Google dictates page rankings. Whilst the variation between a page that has a sub directory (or sub folder) vs when it’s on a sub domain may not always be noticeable, there are instances where choosing either sub domains or sub directories would matter.

The Difference Between a Sub Domain and a Sub Directory

Before we delve into the pros and cons of using sub domains and sub directories for SEO, let’s shed some light into the key differences between them.

Basically, when you use sub domains, your URLs will resemble this:


Notice the ‘subdomain’ right before the main domain? This section relays to Google and your visitors that the content in the sub domain is split from the the rest of your site. A general use for sub domains is whereby its blog can stand on a subdomain (blog.companysite.com for example). Sites that have forums (or article pieces) would usually separate its forum section on a sub domain such as forum.contentsite.com.

Unlike sub domains that come before the domain name, sub directories are the direct opposite. They are usually created as such:


The disparity isn’t just in the syntax. It goes much deeper than that as it correlates with the sort of content you have. There isn’t one fixed rule on when to use sub domains or sub directories but it boils down to this; if the content is good enough to be represented on a separate site, go with a sub domain. For example, if you have a blog about web design, you can position sub directories as guides, free samples or artwork references. Do take note to place the online shop where you sell templates and designs on a separate domain though.

SEO Benefits of Sub Domains

It’s hard to pinpoint if sub domains are indeed more advantageous for SEO as many factors come into play. One thing is for certain; should you have another domain that houses several pages for a single targeted keyword, the benefits are immense.

While Google often restricts the number of search results per domain; this isn’t applicable to sub domains that are relevant. Put simply, if you possess a domain with sub directories and have 10 significant results; Google will often only show 2 or 3 of them, whilst if you have 5 sub domains, it’s likely that 2 or 3 results per sub domain (10-15 together) will be displayed. Although this workaround may be able to trick Google to showcase more results from your end; it isn’t guaranteed that it will work every time.

Another added bonus of using sub domains for SEO is that it allows you to place your keywords as a sub domain. This is especially beneficial should your main domain lack keywords of such nature. If your main domain is educationsomething.com and you have a multitude of content on stationery , it makes sense to create another sub domain.educationsomething.com with your targeted keyword. You could do this with sub directories as well but somehow a sub domain on its own (with its own keyword) has more substance.

SEO Drawbacks of Sub Domains

The pros of using sub domains for SEO purposes are plentiful but they aren’t without their drawbacks. For one, sub domains are harder to implement and manage. Another disadvantage is that sub domains often don’t acquire metrics from the parent domain (i.e. if your parent domain is QR4, your sub domains could be QR0 as Google deems both to be unrelated). For many instances, this could put you off the idea of using sub domains as they don’t; acquire metrics, which means you would have to optimize them from the beginning.