Should I use subdomains or subdirectories from an SEO perspective?

When it comes to search engine optimisation (SEO), the questions that people discuss are almost endless. From time to time we weigh in with advice and one of the things that have been frequently asked is with regards to domains. Specifically, if subdomains or subdirectories (a.k.a. subfolders) is the best option from an SEO perspective? In this article, we elaborate our reasoning on this topic.

Google ‘subdomains vs subdirectories seo’ and you get almost 70 000 hits, so to say that this question is greatly debated is probably an understatement. Unfortunately, it’s hard to find a clear winner empirically based on the results, so what we have done is simply to look for what Google says and does.  

What does Google say and do?

The primary source, as close to an official statement from Google that one can get, is from Matt Cutts who was until recently the head of web spam at Google. Published in October 2012, he addresses this particular issue in a two-minute video.

What he says in the video is that ‘they’re roughly equivalent, I would basically go with whichever one is easier for you’. He then goes on to say that a subdirectory might be easier for some to configure and handle, whereas a subdomain might be the better option when powering e.g. your blog with a different product from your WCMS. 

‘I would basically go with whichever one is easiest for you’

After that he breaks down the history of the debate; where in the distant past subdomains were indeed favoured in search results, which (of course!) marketers noticed and started abusing. That then caused Google to change their scoring, but the debate never ceased to continue.

So hasn’t Google said anything more about this since 2012? Well yes, in various forms and shapes they have. For one, Google themselves are very good at using subdomains as well as subdirectories. For example, they use analytics.google.com, adwords.google.com and plus.google.com, but they also use e.g. google.com/nonprofits or google.com/chrome. 

‘Look at what Google does, and you’ll see they use both.’

Why does Google use both? What is the pattern behind it?

I’ve been looking for an official statement, and the closest I have managed to get is from August 2016 when an analyst from Google’s Webmasters team elaborates on the matter. He basically says that Google is looking at the content of your pages and tries to figure out if it makes sense to treat them as part of the same site or as different sites, regardless of you using subdomains or subdirectories. 

‘So that’s not something that would kind of like improve or hurt rankings. It’s more a matter of us figuring that out. And so far I’ve seen our algorithms do a pretty good job of that.’

Looking at the examples above from Google of how they themselves divide into subdomains and subdirectories knowing this reasoning, it does make sense. Analytics and Adwords are browser-based tools, very different from the core website of google.com whereas Google for nonprofits or Chrome is information pages about products and services Google is offering. 

What does all this tell us?

Based on above, I’m certain that in specific situations it could be more beneficial for you to actively do one thing over the other, rather than having google determining it for you. But I’m also certain that if you’re not equipped with an unlimited budget to investigate your specific situation, then go with what Google says and does and you can sleep well at night.

I’ve been in the business long enough to see recommendations change time and time over in the constant chase between search engine marketers and Google. To stay on top of Google in that chase demands time and resources, so don’t play the game unless you have the intention and means to win.