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SEO Benefits: Subdomain or Subfolder?

Written by Alain Attias

12 | 06 | 15

SEO  |  
3 minute read

Setting up a new website section or blog involves consideration for whether to utilise a subdomain or subdirectory structure. This can be a puzzling decision. To help you make a more informed choice we have provided the considerations, advantages and disadvantages for you.


In the past, Google treated all sub domains as though they were independent domains, a method often referred to as ‘host crowding.’ This posed a problem for Google at the time since they only liked to display up to two results per domain on their results pages. From December 2007 onwards, an algorithm update was introduced to prevent this scenario from occurring again.

Search engines treat subdomains and subdirectories very differently and therefore both types of set up do have implications from an SEO perspective. Having an understanding of how these two options differentiate will provide you with a better chance of increasing your visibility in the search engines.



There are occasions where setting up a subdomain is more preferable and easier for the business due to technical implementation. For example, a new company blog may be better suited for separating the CMS, content, theme and concept. The other benefit to subdomains is from a marketing perspective. By keeping the content on a separate URL e.g. blog.website.com, the brand reputation is being protected more as the content would not be directly on the main website.


One of the disadvantages of opting for the subdomain option is that because the search engines view them as separate sites, they are treated as separate domains when it comes to determining rankings. Considerations need to be made for developing a subdomain into its own entity. This consists of building inbound links from other relevant, established websites and featuring lots of good quality content.

As an example, if the main website has accumulated 1,000 quality backlinks over time, it would now be necessary to build up at least 1,000 quality backlinks for the subdomain if you expect to see similar results. If there are many similar subdomains to target then the workload can really pile up quite quickly.

Lastly, there has been a history of SEOs and Webmasters using subdomains for spam tactics which is a partial reason for Google opting to filter out overly repetitive subdomains being returned in their search results.



Using subfolders as opposed to subdomains has many benefits. Firstly, aside from an SEO viewpoint, folders are a neat way to keep any themed content grouped or categorized and helps to keep web files neatly organised. This is especially useful for larger websites.

In terms of SEO considerations, pages set up in a subfolder-like structure will leverage the ‘power’ of the main domain itself and would receive a trickle-down effect from the inbound links received from the domain itself. For SME who can struggle to build domain authority keeping content within one place will help build authority, as opposed to spreading the content too thinly through using sub domains.


One disadvantage to consider is that the number of pages the URL contains will increase in a sub folder setup. If you have a low authority, having a high amount of page could reduce the rankings of your other pages as the authority is shared over a higher amount of pages. If the content you are placing in your sub folder is much less important than your main content then a sub-domain setup may be better.


When deciding which route to take when setting up your website, both subfolders and subdomains can each be used to market web content differently. Generally speaking from an SEO perspective, is to choose a subfolder structure rather than a subdomain.

The only purpose where a subdomain option would be more preferable is for branding. A Company may be launching a new product, for example, which could be a risk in terms of maintaining a good brand reputation. By creating a subdomain for this product, the content is featured as a separate to the main domain.

One way to think about the different setups is that a sub folder is like a label which describes the meaning of a group of pages within a website whereas a subdomain are actually separate sites in themselves. A combination of utilising both subdomains and subfolders should be considered as a marketing and an information architecture consideration. The subfolder and subdomains can be used to market web content in different ways. Subfolders can describe what individual pages are about whereas the subdomains describe individual sites. Either way, search marketers can and should be considering both options as opposed to choosing one above the other.

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