Do Subdomain Links Count as Backlinks?

Yes. A subdomain is a separate host, so a link from blog.example.com to your site is an external backlink and passes value like any other. What changes is the weight. Google evaluates the subdomain's own authority and its relationship to the parent domain, and most backlink tools roll subdomains into the root domain — so your referring-domain count often will not move at all.

Google treats subdomains case by case

Google's systems decide, per site, whether a subdomain is genuinely a separate property or just part of the main one. support.stripe.com is plainly the same organisation as stripe.com. someshop.myshopify.com is plainly not the same organisation as Shopify.

That distinction drives everything. Google's guidance on site structure treats both subdomains and subdirectories as valid ways to organise a site, and Google representatives have said consistently that the ranking systems handle them largely the same way.

The practical translation for link building:

A link from a subdomain of a company you already have a link from is close to a second link from the same site. Real, but heavily diminished — the mechanics are the same as those in do multiple links from the same site count more than once.
A link from a subdomain that operates as its own publication, with its own audience and its own links pointing at it, carries close to the weight of any independent site.
A link from a bare user subdomain on a hosting platform carries almost nothing, because the subdomain itself has earned nothing.

Your backlink tool is probably lying to you about this

This is the part that causes the most confusion, and it is a measurement artefact rather than an SEO fact.

Ahrefs, Semrush and Moz report referring domains at the root level by default. Links from blog.example.com, shop.example.com and example.com collapse into a single referring domain: example.com. So you can earn three genuine links from three different subdomains and watch your referring-domain count rise by one.

That is not the tools being wrong. It reflects how the weight actually behaves — three links from one organisation are not three independent votes. But it does mean two things:

Do not chase subdomain links to move a metric. The metric is designed not to move. The difference between links and referring domains is worth understanding properly; it is covered in referring domains vs backlinks.
Authority metrics on subdomains are frequently inherited, not earned. This is the single most exploited gap in link buying, and it deserves its own section.

Why "DA 90 backlinks" from free subdomains are worthless

A large share of cheap backlink packages are built on free-subdomain platforms: yourname.wordpress.com, yourname.blogspot.com, yourname.wixsite.com, yourname.github.io, yourname.weebly.com, yourname.notion.site.

The sales pitch writes itself. Run any of those root domains through a metrics tool and you get a Domain Authority in the 90s. The seller screenshots that number and calls it a DA 94 backlink.

What is actually happening: the metric belongs to wordpress.com, a domain with hundreds of millions of links. Your brand-new subdomain has none. It inherits the display number in some tools and inherits none of the ranking value. A page nobody links to, on a host nobody has heard of, passes approximately nothing regardless of what the dashboard says.

Three further problems compound it:

Most of these platforms apply nofollow or ugc to outbound links by default, so there is no signal to pass in the first place. The distinction matters and is set out in dofollow vs nofollow links.
The pages are usually orphaned. Nothing links to them, so they are crawled rarely and sometimes never indexed at all.
The footprint is obvious. Hundreds of near-identical free-subdomain pages pointing at one site is a recognisable pattern, and it is exactly the profile described in what is a link farm.

If you are being sold links on domain metrics alone, check whether the placement URL is a subdomain, and check the metrics for that specific subdomain and page rather than the root. The gap is often the entire pitch. The broader problem with buying on metrics is covered in what is a bad backlink.

Links between your own subdomains are not backlinks

If you run docs.yoursite.com, help.yoursite.com and yoursite.com, links between them will appear in some tools as external links. Treat them as internal linking, because that is what they functionally are.

They are still worth getting right — they help crawlers understand the relationship between your properties and distribute authority across them. But they are not wins, they do not belong in a link-building report, and building more of them does nothing for your off-site profile. The principles that apply are in what are internal links in SEO.

Should your own blog live on a subdomain or a subfolder?

Different question, but it is what most people are really asking when they search this, so it is worth answering directly.

Default to a subfolder — yoursite.com/blog rather than blog.yoursite.com. Not because subdomains are penalised, but because a subfolder removes the question entirely. There is no case-by-case judgement for Google to make about whether the content belongs to the main site; it demonstrably does. Every link the blog earns is unambiguously a link to the same host as your product pages.

Reasons a subdomain is still the right call:

A genuinely different technology stack that cannot be reverse-proxied cleanly
A separate brand, product line or regional entity with its own identity
A user-generated platform where you actively want separation from your main site's reputation
Language or country targeting where the split is intentional

If you already run a subdomain and it performs well, migrating is a real project with real risk. Do it because you have a structural reason, not because of a general claim that subfolders rank better.

Frequently asked questions

Do links from subdomains count as backlinks? Yes. A subdomain is a distinct host, so the link is external and passes value. The weight depends on the subdomain's own authority and whether Google associates it with the parent domain — links from a subdomain of a site already linking to you add much less than a new referring domain.

Will subdomain links increase my referring domain count? Usually not. Ahrefs, Semrush and Moz group subdomains under the root domain by default, so several links from different subdomains of one site typically register as a single referring domain.

Are free subdomain backlinks like WordPress.com or Blogspot worth building? No. The high authority score belongs to the platform's root domain, not to your subdomain, which has earned nothing. Outbound links on those platforms are also commonly nofollow or ugc-tagged, and mass-built profiles form an obvious footprint.

Do links between my own subdomains help SEO? They function as internal links rather than backlinks. Worth structuring properly so crawlers understand your properties, but they do not strengthen your off-site link profile and should not be counted as link-building results.

Is a subdomain or a subfolder better for a blog? A subfolder is the safer default because it removes any ambiguity about whether the content belongs to your main site. Subdomains are fine when there is a genuine structural reason — a separate stack, brand or region.

Does a link from a subdomain pass less link juice than the root domain? It depends on that subdomain's own authority and the page the link sits on, not on the fact that it is a subdomain. A well-established subdomain publication can pass as much as an independent site; an empty user subdomain passes essentially nothing.

The bottom line

Subdomain links count, and they are worth having when the subdomain is a real property with a real audience. They are not worth buying when the only thing supporting the price is a root-domain metric the subdomain did not earn. Check the metrics for the exact host and the exact page, not the domain in the sales screenshot.

The reliable version of this is a link from a site that genuinely exists, on a page that genuinely gets read. Backlinkster matches real site owners for one-for-one in-content swaps and verifies every placement live by code, so what you get is what was agreed. Five swaps a month on the free plan; see the plans.