When you’re building or scaling a website, one of the biggest structural decisions you’ll face is whether to organize your content under a subdomain or a subdirectory. This isn’t just a matter of preference it can significantly affect your SEO performance, crawlability, and user experience.
So, which one is better for SEO? In this guide, we’ll break down the differences, explain the advantages and drawbacks, and help you choose the best setup for your specific goals.
What’s the Difference Between a Subdomain and a Subdirectory?
Let’s start with the basics.
- MỘT subdomain is a separate part of your main domain that functions like its own site.
Example: blog.example.com - MỘT subdirectory is a folder within your main domain that shares the same backend and structure.
Example: example.com/blog
While they may seem interchangeable, search engines and users don’t always treat them the same. Subdomains often operate with their own ecosystem separate codebases, content teams, and even analytics. Subdirectories, on the other hand, keep everything under one digital roof.
Knowing when to use each can have a big impact on your long-term SEO success.
How Google Treats Subdomain vs Subdirectory
Google has officially stated that it can crawl and index both subdomains and subdirectories equally well, and that neither structure is automatically favored in its search algorithm. According to Google representatives like John Mueller, “Google is smart enough to recognize that a subdomain is part of the same website if it’s clearly connected.”
However, the reality experienced by SEOs and webmasters paints a more nuanced picture. In practice, how your website is structured can still influence crawling efficiency, domain authority distribution, and how easily new content gets discovered and ranked.
Let’s break it down further:
Subdomains: Treated as Separate Sites
When you create a subdomain such as blog.example.com hoặc shop.example.com Google treats it as a separate web property from your main domain (example.com). That means:
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Separate SEO strategies: You’ll need to optimize each subdomain independently, including conducting keyword research, creating targeted content, and building topical relevance.
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Dedicated backlink profiles: Backlinks to a subdomain generally don’t pass the same ranking value to the root domain as internal subdirectory links do. You need to build trust and authority for each subdomain almost from scratch.
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Independent content optimization: Metadata, structured data, page speed, and on-page SEO must be handled independently for each subdomain.
Because of this separation, many websites struggle to gain momentum across multiple subdomains unless they have a strong team and resources to handle each one individually.
Potential downside?
If you split your blog, shop, academy, or support center into subdomains without building their authority, it can dilute your overall SEO performance. This is especially risky for small to mid-sized websites that don’t have the resources to grow each subdomain separately.
Subdirectories: Part of the Main Domain
Subdirectories such as example.com/blog hoặc example.com/shop are considered integral parts of your main site. Google treats them as an extension of your root domain, which comes with some key SEO benefits:
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Shared link equity: When you build backlinks to your main domain, all internal subdirectories benefit from that authority. This makes it easier for your new pages or blog posts to rank without starting from zero.
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Centralized crawl budget: Google assigns each domain a “crawl budget” (i.e., how often and how deeply it crawls your site). With subdirectories, everything is under one roof, making it easier for Google to crawl and index content quickly and consistently.
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More efficient SEO management: Since everything lives within the same domain, it’s easier to manage your site structure, internal linking, analytics, and overall content strategy.
That’s why many SEO professionals strongly recommend using subdirectories for sections like blogs, landing pages, or knowledge bases especially when the content is closely tied to your main business offerings.
The main advantage?
All of your content works together to improve your domain’s overall SEO strength, making it easier to grow and rank over time especially when targeting competitive keywords.
In summary, while Google says it can handle both formats equally, subdirectories typically offer an SEO advantage due to shared authority and simplified management. Subdomains are not inherently bad, but they require more time, effort, and precision to achieve similar results.
Want to build smarter site architecture from the start? Stick with subdirectories unless your business has strong technical reasons to branch into subdomains.
Pros and Cons of Subdomains for SEO
Using subdomains isn’t necessarily bad it all comes down to context. Here’s a deeper look at the advantages and disadvantages:
Ưu điểm:
- Content Separation: Ideal for running sections of your site that are managed by different teams, like a customer support portal or a forum.
- Platform Flexibility: You can use a different CMS or tech stack on a subdomain without affecting your main site.
- Cleaner Scaling for Large Businesses: Corporations with many verticals or brands often prefer subdomains for clarity and scalability.
Nhược điểm:
- SEO Fragmentation: You may need to build SEO authority from scratch on each subdomain.
- Duplicate Effort: Content optimization, analytics setup, and keyword strategies need to be repeated for each subdomain.
- Harder to Build Domain Authority: Backlinks to subdomains don’t always pass value to your root domain.
Đọc thêm: What is a Subdomain? How It Works and Why It Matters
Pros and Cons of Subdirectories for SEO
Subdirectories are generally more SEO-friendly for smaller to mid-sized sites, and even for large brands focused on unified growth.
Ưu điểm:
- Consolidated Authority: All your backlinks, content, and keyword rankings contribute to one domain boosting visibility site-wide.
- Simplified SEO Strategy: You can optimize everything from one place, track results easily, and improve performance faster.
- Efficient Indexing: Google crawlers index content in subdirectories more efficiently, especially if your internal linking is well structured.
Nhược điểm:
- Technical Constraints: If your blog or shop requires a completely different system, it might be harder to manage in a subdirectory.
- Risk of Overcrowding: Without clear architecture, subdirectories can become cluttered, which may impact UX and crawlability.
Real-World Examples to Learn From
Let’s look at how some industry leaders approach this decision:
Subdomain Example: HubSpot
HubSpot runs its blog on blog.hubspot.com. Although it requires separate SEO efforts, HubSpot has the resources to grow both properties independently and build strong authority for each.
Subdirectory Example: Shopify
Shopify uses shopify.com/blog. This helps consolidate link equity and makes their blog a powerful part of their core domain strategy ideal for boosting their SEO on transactional and informational queries alike.
These examples prove that both models can work well, but only if they align with your content strategy and SEO bandwidth.
When to Use Subdomains vs Subdirectories
Here’s a more practical guide to help you choose:
|
Scenario |
Best Option | Why |
|
Running a multilingual site with different regions |
Subdomain |
fr.example.com, us.example.com keeps regions separated |
| Starting a company blog | Subdirectory |
example.com/blog benefits from main domain SEO |
|
Creating a support portal or documentation site |
Subdomain | Ideal for separation and unique design |
| Expanding your e-commerce store | Subdirectory |
Easier to manage and scales SEO more efficiently |
| Hosting a staging or development site | Subdomain |
Keeps testing environment safely isolated |
Which One Is Better for SEO?
Here’s the honest answer: Subdirectories generally outperform subdomains in SEO if you’re trying to grow a cohesive site under one brand.
But if you need more separation whether it’s technical, operational, or strategic subdomains give you that flexibility.
Choose subdirectories if:
- You want to build domain authority fast
- You’re running a single brand with unified goals
- Your SEO team is small or limited in resources
Choose subdomains if:
- You have separate teams managing each section
- You need to run different platforms or CMSs
- You’re targeting multiple markets with distinct content
Suy nghĩ cuối cùng
Choosing between a subdomain and subdirectory is not just a technical decision it’s a strategic one that influences how users and search engines interact with your content. While subdirectories often offer a stronger SEO edge, subdomains still have their place in complex web environments.
The golden rule: Choose the structure that supports your long-term content strategy, team capabilities, and brand architecture.
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