In short
Domain Authority is a metric created by Moz, scored 1 to 100, that predicts how well a domain is likely to rank based mainly on the quantity and quality of links pointing to it; Ahrefs' Domain Rating and Semrush's Authority Score are equivalents. Google does not use Domain Authority or any of these scores, and its representatives have said repeatedly that it has no single site-wide authority metric of the kind they imply. The scores correlate with rankings because links matter, and they are useful for comparing sites at a glance and for rough link prospecting; they are not a goal, a ranking factor, or a measure of a site's quality.
What it is
Moz introduced Domain Authority in the late 2000s as a way of summarising a site's link profile in one number. It is a machine-learning model trained to predict rankings, fed mostly with link data: how many domains link to a site, how strong those linking domains are, and related signals. The output is a logarithmic score from 1 to 100, so moving from 20 to 30 is far easier than from 70 to 80, and the score is relative, recalibrated as the web changes, so a site's DA can fall without anything changing on the site.
Ahrefs' Domain Rating and Semrush's Authority Score do the same job with different data and models, which is why the three disagree about any given site. Each is a prediction of Google's behaviour by a company that observes Google from outside.
| Score | Made by | Used by Google? |
|---|---|---|
| Domain Authority | Moz | No |
| Domain Rating | Ahrefs | No |
| Authority Score | Semrush | No |
What Google says
Google's representatives have been asked about Domain Authority for over a decade, and the answer has been consistent: Google does not use Domain Authority, does not use any third-party score, and does not have an internal metric that corresponds to it. Google's systems evaluate pages, links, and a range of site-level signals, but the idea of a single site-wide authority number that determines rankings is a simplification made by tools, not a description of how Google works.
That does not mean links do not matter, or that Google ignores site-level quality. It means the specific number in your SEO tool is the tool's opinion, not Google's.
Why the scores still correlate with rankings
Because links matter and the scores measure links. A site with many links from strong sites tends to rank well, and tends to have a high DA, so DA and rankings move together. That is correlation through a shared cause, not DA causing rankings. The same reasoning explains why a high-DA site can rank badly for a query it has no relevant page for, and why a low-DA site with the best page on a specific topic can outrank it: the score does not know what the pages say.
How the scores mislead
As a target. "Get our DA to 50" is a goal that can be met by acquiring links that raise the score and do nothing for rankings or business, which is what most link-buying produces. The score is not the thing.
As a quality measure. DA says nothing about content, expertise, user experience or whether the site is trustworthy. Spam sites with manufactured link profiles have high scores; excellent small sites have low ones.
As a comparison across tools. A DA of 40, a DR of 55 and an Authority Score of 35 for the same site are not contradictions; they are three models with three scales.
As a stable number. Scores are recalibrated periodically. A drop in DA with no change in rankings or traffic means the model moved.
As a link-selling metric. "DA 50 guest post, $200" is an advertisement for a link scheme, and the score is being used precisely because it can be inflated. Our note on whether backlinks still matter covers what actually counts.
What the scores are legitimately good for
Comparing sites quickly. Deciding whether a potential link source is a real site with a real profile or a thin one, before looking closer.
Sizing up competitors. A rough sense of whether the sites ranking for a target term have far stronger link profiles than yours, which informs how long a ranking campaign will take.
Tracking your own link profile's direction over time, alongside the actual referring-domain counts the score summarises.
Communicating to non-specialists, with the caveat attached, that a site's link profile is growing or not.
In each case the score is a shortcut for looking at the links themselves, and the links themselves are what to look at when it matters.
What to track instead
Referring domains, and their relevance and quality, which is what DA compresses. Rankings and clicks for the queries that matter, from Search Console. Branded search volume, which reflects real-world prominence in a way no link model can. Pages indexed and their performance. Conversions from organic traffic. Every one of these is a measure of something Google actually responds to or something the business actually needs; DA is a measure of a model's opinion of the first item on the list.
The short answer
Domain Authority is a useful third-party estimate of link strength, one of several, and Google does not use it. Use it to compare and prospect, report referring domains and rankings instead of the score, and treat any offer priced by DA as what it is. If someone has told you your DA is the reason you do not rank, book a call; the actual reason is usually on the page.
Common questions
Is Domain Authority a Google ranking factor?
No. Domain Authority is a metric created by Moz that predicts ranking strength from link data. Google has said repeatedly that it does not use Domain Authority or any third-party score, and that it has no equivalent single site-wide authority number. The score correlates with rankings because links matter, not because Google reads it.
What is a good Domain Authority score?
Relative to competitors, not absolute. The scale is logarithmic, so most small business sites sit between 10 and 40, established brands between 40 and 70, and major publishers and platforms above that. A site whose DA is close to the sites ranking for its target terms can compete on content; one far below faces a longer link-building path.
Why did my Domain Authority drop?
Usually because Moz recalibrated its model or index, which changes scores across the web without anything changing on your site, or because some referring domains were dropped from its index or lost their own authority. If rankings and traffic are unchanged, the drop reflects the tool, not Google.
What is the difference between Domain Authority and Domain Rating?
Domain Authority is Moz's score and Domain Rating is Ahrefs'; Semrush has Authority Score. Each predicts ranking strength mainly from link data using its own crawl and model, so the numbers differ for the same site and are not comparable across tools. None is used by Google.
How do I increase my Domain Authority?
By earning links from genuine, relevant sites, which is the same work that improves rankings. Treat the score as a side effect rather than a goal: links bought to raise DA raise the number without helping rankings and can attract penalties. Track referring domains, rankings and branded search instead of the score.
