Subdomain vs Subfolder
A subdomain is a separate hostname before the root domain (like blog.example.com), while a subfolder is a path inside the main site (like example.com/blog).
The short call
- Start with subfolders unless you have a clear reason for separation.
- If you use subdomains, invest in cross-linking and shared navigation.
- Plan redirects and tracking continuity before any URL structure change.
- Use Google Search Console to monitor how your chosen structure is indexed.
- Test with a small section before migrating a whole site.
Here's the quick breakdown so you can stop guessing and start building.
Side by side
| A: Subfolder | B: Subdomain | |
|---|---|---|
| URL example | example.com/blog | blog.example.com |
| Authority flow | Shares authority with main domain | Builds separate authority (unless cross-linked) |
| Technical independence | Same hosting, CMS, security boundaries | Can use separate hosting, CMS, or security |
| Setup complexity | Lower – just add a directory | Higher – requires DNS config and often separate server |
| Internal linking | Easier – same domain, relative links work | Harder – need absolute links and careful cross-linking |
| Crawl budget | Shared with main domain | Separate – may need its own crawl budget management |
| Best for | Content that supports main site (blog, resources) | Separate products, different languages, or independent apps |
How I'd choose
- Go subfolder when:
- Your content is closely related to the main site (e.g., a blog about your product).
- You want to consolidate link equity and ranking signals.
- You have one team managing everything and don't need separate infrastructure.
- You're starting fresh and want the simplest setup.
- Go subdomain when:
- You need a different CMS or hosting environment (e.g., a WordPress blog on a separate server).
- The content targets a different audience or language (e.g., en.example.com for English).
- You want strict security or compliance boundaries (e.g., a payment portal).
- You're running a separate web app that has its own domain logic.
Shared pitfalls
- Assuming they're interchangeable. They're not. Subdomains split authority; subfolders pool it. Pick based on your goals, not habit.
- Moving content without redirects. If you switch from subdomain to subfolder (or vice versa), set up 301 redirects and update internal links. Otherwise you'll lose traffic and confuse search engines.
- Forgetting cross-linking. If you use a subdomain, you need to actively link between it and the main domain. Don't assume Google will connect them automatically.
- Ignoring crawl budget. A subdomain can eat into your main domain's crawl budget if not managed properly. Use robots.txt and sitemaps to guide crawlers.
- Choosing subdomain by default. Many people pick subdomain because they've seen it before, but for most content sites, subfolders are easier and more effective for SEO.
Quick answers
Does Google prefer subfolders over subdomains?
Google has said both are fine, but many SEO case studies show subfolders tend to rank better because they consolidate authority. It depends on your specific setup and goals.
Can I switch from subdomain to subfolder without losing rankings?
Yes, but you need to plan carefully: set up 301 redirects, update internal links, and monitor traffic in Search Console. Expect a temporary dip during the transition.
Sources
Primary documentation is linked directly. Anything commercial is marked nofollow.
- Google Search Central — Primary source for Google guidance on site structure and indexing.
- Moz — Widely cited SEO reference for architecture and authority flow comparisons.
- Search Engine Journal — Practical editorial SEO guidance with implementation examples.
Notes from Callum Bennett.