Definition
A referring domain is a website that links to yours at least once, counted once however many links it sends. There is no standard behind the number. Each backlink tool decides what counts as a domain and counts from its own crawl, so the same site gets a different figure in every tool.
Example. A news site that links to you from 40 articles gives you 40 backlinks and 1 referring domain.
You can find the referring domains that link to your competitors and not to you with the free Backlink Gap Finder, which counts them from SE Ranking's link index.
Why does every backlink tool report a different number?
Every tool reports a different number because each one defines a domain its own way and counts from its own crawl. Ahrefs describes the choice: treat every registered domain as one domain, or treat every subdomain as a separate one. Ahrefs takes a middle path, breaking out some subdomains such as those on blogspot.com, and states plainly that different domain definitions can produce large variations in referring domain counts.
The practical rule follows from that. Compare referring domains within one tool, never across two. Your figure in one tool against a competitor's figure in another is a difference between two crawlers, not between two sites, and a domain missing from a tool is unknown to that tool, not proof the link does not exist.
What does Google show you about referring domains?
Google shows you a sample, not a full list. The Search Console Links report has a Top linking sites table: the root domains with the most links to your site, sorted by link count. Google says the report is not a comprehensive list of every link, and caps its tables at 1,000 rows.
| Question | Search Console Links report |
|---|---|
| Complete list? | No. A sample of the links Google found over time |
| Subdomains | Merged into their root domain. Different top level domains stay separate |
| Nofollow | Not indicated |
| Rows | Capped at 1,000 per table |
Is a referring domain count a measure of link quality?
A referring domain count is not a measure of quality. It tells you how many sites link to you, not which ones or why. Ten sites that link because your page earned it and ten that were paid to link produce the same count, and only one of those groups is worth having. The good vs bad backlinks guide covers how to tell them apart.
Sources
- Ahrefs: How Ahrefs counts links and domains (January 2021)
- Semrush Knowledge Base: Domain Overview, Referring Domains metric
- Search Console Help: Links report
Last checked against these sources on 19 October 2026.