Definition
Domain Authority is a score from 1 to 100 that the SEO tool Moz gives a website to predict how well it can rank. Moz works it out with a machine learning model, mostly from the links pointing to the site. It is Moz's own measure, and Google has said search engines do not use it.
Example. A site Moz scores 40 and a site Ahrefs rates 40 have two different measurements, taken by two different crawlers (the programs each tool sends to read the web). Compare each one only with its own tool's scores.
You can compare authority scores for the sites linking to your competitors with the free Backlink Gap Finder, which shows SE Ranking's InLink Rank.
Does Google use Domain Authority?
Google does not use Domain Authority. It is a score made by Moz, and Google has said so more than once. Google's John Mueller has said it twice in public: "Search engines don't use it," and in 2019, "We don't use domain authority." Moz itself calls the score a comparative metric.
Why does every SEO tool have its own authority score?
Every SEO tool has its own authority score because each one builds it from its own crawl of the web and its own formula. The numbers sit on similar scales but measure different things, so a 40 in one tool and a 40 in another measure two different things.
| Tool | Score | What the tool says it measures |
|---|---|---|
| Moz | Domain Authority, 1 to 100 | How likely a site is to rank, from a machine learning model built mostly on link data |
| Ahrefs | Domain Rating, 0 to 100 | The strength of a site's backlink profile compared with the other sites in its database |
| Semrush | Authority Score | Link power, plus estimated organic traffic and spam checks |
| SE Ranking | Domain InLink Rank, 0 to 100 | Link strength from SE Ranking's own link index |
We made this mistake ourselves. Our Backlink Gap Finder first labelled SE Ranking's score "DR", which is Ahrefs' name for a different number. We relabelled it InLink Rank in October 2026, with the tool named beside it.
How should you read a domain authority score?
Read a domain authority score against other scores from the same tool only. It is a quick way to sort a list of sites. What makes a link good is the reason a site links to you, and only reading the linking page tells you that. The referring domains behind it, and why they link, tell you more.
Sources
- Moz: What is Domain Authority?
- Ahrefs Help Center: What is Domain Rating (DR)?
- Semrush Knowledge Base: Authority Score
- Search Engine Journal: Is Domain Authority a Google ranking factor?
Last checked against these sources on 8 November 2026.