What Are Referring Domains? (And Why They Matter for SEO)

If you have ever looked at a backlink report and wondered what the difference is between "backlinks" and "referring domains", you are not alone. The two terms are often used interchangeably, but they measure different things, and the distinction matters for how you interpret your link data.

The short answer

A referring domain is a unique website that links to your site. A backlink is an individual link instance.

If a single website links to your site from ten different pages, that counts as one referring domain but ten backlinks.

Why referring domains matter more than backlinks

Search engines care about diversity. A hundred links from a hundred different websites signals broad trust across the web. A hundred links from one website, no matter how authoritative, does not carry the same weight.

This is why referring domains is considered the more meaningful metric in backlink analysis. Google's PageRank algorithm treats links as votes, and votes from many different sources carry more credibility than many votes from a single source.

Industry data supports this. Pages ranking in the top three positions on Google consistently have significantly more referring domains than pages further down the results. The relationship between referring domain count and ranking position is one of the most consistent signals in SEO research.

How to check referring domains

You can check referring domains for any website using Crawly's backlink checker. Enter any domain and the tool returns:

• The total number of referring domains
• A breakdown by link quality (High, Medium, Low)
• PageRank rank with a global percentile
• The full list of linking domains, filterable and exportable

No account or subscription is needed.

Referring domains vs backlinks: a practical example

Imagine two sites, A and B, both trying to rank for the same keyword.

• Site A has 200 backlinks from 8 referring domains
• Site B has 80 backlinks from 60 referring domains

In almost every case, Site B has the stronger profile. Its links come from a wider variety of sources, which looks more natural and carries more trust.

This also explains why link schemes that rely on a small network of sites to generate large numbers of links tend to be ineffective or actively harmful. Google can see when link diversity is low and discounts or penalises accordingly.

What counts as a good number of referring domains?

There is no universal benchmark. What matters is how your referring domain count compares to the pages you are competing against.

If you are trying to rank for a competitive keyword, check the backlink profiles of the pages currently ranking in the top five. How many referring domains do they have? That gives you a realistic target for your own link building efforts.

For local businesses and niche sites, 50 to 100 high-quality referring domains is often more than enough to rank well. For competitive national or global terms, the bar is considerably higher.

Do all referring domains count equally?

No. A referring domain from a major national newspaper carries far more weight than a link from a low-traffic blog with no authority. The quality of referring domains matters as much as the quantity.

The key factors that affect how much weight a referring domain passes include:

• Authority. Sites with strong backlink profiles of their own pass more PageRank than those with few or weak links.
• Relevance. A link from a site in the same industry or topic area is typically more valuable than a link from an unrelated source.
• Traffic. Sites with genuine organic traffic are generally more trusted by search engines than low-traffic sites.
• Link placement. Editorial links within body content carry more weight than links in footers, sidebars, or directories.

Toxic referring domains

Not all referring domains are helpful. Links from very low-quality sites, link farms, or spam networks can be actively harmful to your rankings. These are sometimes called toxic referring domains.

Crawly's backlink checker flags domains ranked below 50 million globally as potentially toxic. If your profile contains a significant number of these, it may be worth building a Google disavow file to tell Google to ignore them.

How to grow your referring domain count

Growing your referring domain count is the goal of link building. The most sustainable approaches are:

• Creating linkable assets. Original research, tools, guides, and datasets attract natural links because other sites want to cite them.
• Earning editorial coverage. Getting mentioned in relevant publications, podcasts, or industry blogs builds diverse, high-quality referring domains over time.
• Competitor gap analysis. Find sites linking to your competitors but not to you, then give them a reason to link to you as well.

For a detailed walkthrough of finding competitor links, see how to find and analyse competitor backlinks.

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Referring domains is one of the clearest signals of a site's authority and link-building progress. Tracking it monthly with Crawly's backlink tool is one of the simplest and most effective SEO habits you can build.