Subdomain or subdirectory: which is better for SEO?

When you add a blog, a shop, or a section in another language, you eventually hit the same question: should it be a subdomain (blog.mysite.com) or a subdirectory (mysite.com/blog)? The decision looks purely technical, but it has direct consequences for SEO and for how quickly the new section starts ranking on Google.

What the difference really is

A subdirectory is a path inside the same domain — mysite.com/blog. To Google''s systems it is an inseparable part of the main site. A subdomain (blog.mysite.com) is technically a separate host that Google often treats as a partly independent entity. Both sit under the same brand, but authority — links, trust and indexing history — does not always transfer equally.

How Google treats each approach

Google officially states it can handle both equally well. In practice, subdirectories tend to inherit the main domain''s authority faster, because every signal (backlinks, clicks, trust) accumulates on a single host. Migration case studies have repeatedly shown traffic jumps of 20–60% after moving content from a subdomain into a subdirectory. A subdomain has to build part of its reputation on its own, which means a slower start for a new site.

When a subdomain still makes sense

• A technically separate platform: if the blog runs on a completely different system, a subdomain simplifies hosting and maintenance.
• A genuinely different audience or purpose: support (help.mysite.com) or a status page naturally live apart.
• Large independent regional units: sometimes used for major standalone markets.

When to choose a subdirectory (most of the time)

For a blog, product categories, and any content that needs to rank as soon as possible, a subdirectory is almost always the safer choice. All the SEO equity stays on one domain, internal linking feels natural, and Google connects new content to existing authority faster. If you are building a multilingual website, subdirectories like /en/ and /de/ pair perfectly with hreflang tags and are easier to maintain than separate subdomains.

Practical takeaway

Unless you have a strong technical reason to split things apart, stick with a subdirectory. Once you decide, set correct canonical tags and watch your crawl budget so you don''t waste resources on duplicates. Hosting speed also affects how efficiently Google crawls your site — reliable SEO hosting with NVMe drives and a global CDN gives you a solid base regardless of URL structure. See our plans if a migration is on the horizon.