Referring domains vs backlinks: the difference

Both numbers sit side by side on every backlink report, and they rarely match. In a sample of 55 domains we measured on 2026-10-02, the median site had about five backlinks for every referring domain. That is not an error in the data. One number counts links, the other counts the sites the links come from, and the second is the better guide to how strong a site is. You can see your referring domains and backlinks on our free checker, next to a third count, referring root domains, explained below.

Backlinks vs referring domains: the difference

A backlink is a link on another website that points to yours. A referring domain is the website that link sits on. Ahrefs' help centre puts the counting rule plainly: "If it has two backlinks from the New York Times, then it still has one referring domain."

	Backlinks	Referring domains
What is counted	Every link from another site to yours	Each linking website, once
A local paper mentions you in one article	1	1
A blogger links to you from 40 posts	40	1
A partner adds your link to its site-wide footer	One per page on their site	1
What the number tells you	How many links exist	How many sites vouch for you

An example of a backlink, since that is usually the first question: a regional news site writes about a bakery and links the bakery's name to its homepage. That is one backlink, and the news site becomes one referring domain. If the paper later links to the bakery from four more articles, the backlink count rises to five and the referring-domain count stays at one.

Why referring domains matter more than backlink counts

A tenth link from a site that already links to you adds very little. Ahrefs builds its Domain Rating on exactly that rule: "subsequent links from the same website won't improve a site's DR since we count referring domains and not backlinks." Backlinko gives the same advice in round numbers, "it's better to earn links from 100 different sites than 1,000 from the same site", and reports that in its ranking correlation study the number of sites linking to you, rather than the total number of backlinks, correlated with Google rankings more than any other factor.

Traffic data points the same way. Ahrefs found that "the vast majority of pages (of analyzed ~ 1 billion pages) without any referring domains get no traffic from Google", and that search traffic rises with the number of unique referring domains. Ahrefs is careful to say that correlation is not causation, and so should anyone repeating it: the sites that earn links from many places are usually also the sites publishing things worth linking to. The practical reading holds either way. When you plan link work, count new domains rather than new links, and value a link from a site that has never linked to you above another from one that already does. The page on how to earn links from new domains covers the tactics that work for a small site.

Referring root domains and subdomains

Our checker, which uses DataForSEO's link index, counts a subdomain as its own referring domain, so a link from blog.example.com and another from shop.example.com are two referring domains. Both belong to one root domain, example.com, and the root-domain count merges them. That is the third number on the panel, referring root domains. Moz's tools call the same idea linking root domains.

The two counts normally move together: in our sample, the root-domain count was a median of 95 percent of the referring-domain count. A wider gap appears when many links come from a platform that gives each user a subdomain, such as a hosted blog service, where hundreds of separate blogs share one root domain. When the two differ, the root-domain count is the more conservative measure of how many independent sites link to you.

How many referring domains you need

There is no site-wide number to aim for, because the bar is set by the pages already ranking for the keyword you want. Count the referring domains of the top few results for that keyword, and you have a target for that one page.

For a sense of scale, here are the medians from our sample, grouped by each site's Ahrefs Domain Rating and counted in the same index our checker uses. Sites rated DR 20 to 39 had a median of 240 referring domains, DR 40 to 59 had 716, DR 60 to 79 had 1,561, and DR 80 to 89 had 16,789. The sites below DR 20 had a median of 263, more than the band above them, which is a useful reminder that a count is not a strength. Apart from the two indexes counting slightly differently, a lower rating on more domains points to linking sites that are weaker, link out to many others, or use nofollow links, which Ahrefs leaves out of its rating. The blog post on how many backlinks a new site needs walks through that count step by step.

How Structura handles this

Structura does not build links. It sends no outreach, buys nothing and places no links on other sites, so the referring domains a site gains come from people choosing to cite it, or from link work you or your PR do alongside it.

What Structura changes is what there is to cite and how far the links you already have can take you. On paid plans, each post starts from a keyword the site can realistically win at its current strength, is written after a read of the pages already ranking for it, and cites two to four sources from a list you approve; with internal linking switched on, it also links into your existing posts, so the links any one page earns reach the rest. A site with few referring domains gets its first search traffic from those winnable keywords, and an archive of specific, well-sourced answers is the kind of page other sites link to without being asked. The blog SEO software page shows how keywords are matched to a site's strength and what each post includes.

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