What is Domain Authority (DA)?
Domain Authority (DA) is a score from 0 to 100, made by the SEO software company Moz, that predicts how well a website is likely to perform in search rankings [1]. A local bakery's new website might sit in single digits, while a national newspaper sits near the top of the scale.
DA is built mainly from links: how many other sites link to a domain, and how strong those linking sites are in turn. It is a forecast made by a software company from its own crawl of the web. It is not a number Google calculates, publishes or reads.
The term causes constant confusion because "domain authority" is also used loosely, in lowercase, to mean a site's general standing in its field. When someone says a site "has a lot of authority", they may mean its reputation, its rankings or its Moz score. This entry is about the Moz metric. When a client, seller or report quotes "DA 50", it is the Moz metric they mean.
Does Google use Domain Authority?
No. Domain Authority is a Moz metric calculated outside Google, and Google's ranking systems do not read it. Moz cannot see inside Google's systems, and Google has no access to, or reason to use, a third-party score built from another company's crawl.
Google did once show a public link score of its own. Toolbar PageRank displayed a score for pages in the Google Toolbar. Google stopped updating it in late 2013 and removed it from public view in 2016, while PageRank itself continued to be used internally [3][4]. Since then, Google has not published any page or domain score. DA and its rivals filled that gap, which is part of why people mistake them for Google numbers.
Google's spam policies treat buying or selling links "for ranking purposes" as link spam [5]. Nothing in Google's rules mentions DA, and a higher DA earns nothing from Google on its own.
What is a good Domain Authority score?
There is no universally good Domain Authority score. DA is most useful as a comparison: a site's DA means something next to the DA of the sites it competes with for the same searches, and very little on its own.
A practical way to read DA:
- Compare within a niche. A DA of 25 can be strong for a local trades business and weak for a national retailer.
- Compare against the sites that rank. Look at the DA of the pages on page one for your target searches. If they all sit far above you, you have a link gap to close. If they sit near you, other factors decide the ranking.
- Watch the direction, not the number. A steady rise over time, alongside rising traffic, is a better sign than any single score.
Ahrefs describes its own comparable metric, Domain Rating, as "plotted on a logarithmic scale from 0 to 100" [2]. Scales built that way get harder to climb the higher you go, so the gap between 70 and 80 is far larger than the gap between 10 and 20.
What is the difference between Domain Authority and Domain Rating?
Domain Authority is Moz's score and Domain Rating (DR) is Ahrefs' score. Both run from 0 to 100 and both are driven by backlinks, but each company calculates its score from its own crawl of the web with its own model, so the same site gets different numbers.
| Domain Authority (DA) | Domain Rating (DR) | Authority Score (AS) | |
|---|---|---|---|
| Made by | Moz | Ahrefs | Semrush |
| Scale | 0 to 100 | 0 to 100 (logarithmic) [2] | 0 to 100 |
| Built mainly from | Links in Moz's index | "Size and quality of the links" in Ahrefs' index [2] | Semrush's own data |
| Used by Google | No | No | No |
The three scores agree more than people expect. A 2023 study in Profesional de la información by Reyes-Lillo, Morales-Vargas and Rovira compared DA, DR and Semrush's Authority Score and found very high correlation between all three, around 0.9 [1]. The scores rank sites in roughly the same order even when the numbers differ. A site that is DA 40 and DR 55 is not contradicting itself: the two tools use different scales.
Ahrefs is candid about what its version does not measure. It says DR is "not a good indicator of a website's quality or legitimacy; it's merely a measure of 'link popularity'", and recommends pairing it with search traffic [2]. The same caution applies to DA.
Why did my Domain Authority change?
Domain Authority changes when the links Moz sees pointing at a site change, or when the scores of other sites change around it. Because DA is a model run over Moz's own link index, a site's score can move for reasons that have nothing to do with the site itself:
- Links gained or lost. New links from strong sites push DA up. Links that are removed, or sites that disappear, pull it down.
- Moz's crawl changes. Moz cannot crawl the whole web. If it finds or drops links in a recrawl, scores move.
- Other sites move. DA is relative. If many sites gain links faster than yours, your score can slip even though nothing changed.
A DA drop on its own does not mean Google rankings will drop. Google never saw the number. Check real organic traffic and rankings before reacting to a third-party score.
Can Domain Authority be manipulated?
Yes. Because Domain Authority is calculated mainly from links, any link a third-party crawler counts can raise it, whether or not the link carries real value. Sites can be built up with links from low-quality sources, link networks or expired domains to show a high DA while having little real audience. Search Insider covers this pattern in DR inflation.
Search Insider does not support or suggest using private blog networks, and buying links to pass ranking value is a breach of Google's spam policies whatever score the linking site shows [5].
The quickest check against an inflated score is traffic. A site with a high DA and almost no organic search traffic is a warning sign. Ahrefs found that 96.55% of pages in its index get no traffic from Google at all [6], so real traffic is a far stronger filter than any authority score.
How has Domain Authority's role changed over time?
Domain Authority rose as the public's view into Google's own link scores closed. When Google stopped showing Toolbar PageRank, third-party scores like DA, DR and Authority Score became the default shorthand for a site's link strength [3][4].
2013: the last Toolbar PageRank update
Google last updated the public Toolbar PageRank in late 2013 [3][4]. From then on, the only widely available link strength numbers came from SEO tool companies.
2016: Toolbar PageRank removed
Google removed Toolbar PageRank from public view in 2016, while continuing to use PageRank internally [3][4]. Third-party scores, with DA among the best known, took over as the shorthand buyers and sellers quoted.
2023: DA, DR and AS compared
A 2023 academic study compared Moz's Domain Authority, Ahrefs' Domain Rating and Semrush's Authority Score and found very high correlation between the three, around 0.9 [1]. The tools broadly agree on which sites are strong, even though their numbers differ.
How should you use Domain Authority when vetting links?
Use Domain Authority as one input among several, never as the deciding number. A useful order of checks for any site you might get a link from:
- Relevance. Does the site cover your topic, and would its readers care about your page?
- Real traffic. Does the site get meaningful organic search traffic, and is it stable or rising? See traffic-validated link.
- Link strength. Then look at DA or DR, compared with other sites in the same niche.
- Outbound link pattern. Does the site link out to everyone on any topic? That suggests links are for sale.
- How the link will be marked. A paid placement must carry
sponsoredornofollowunder Google's rules [5].
A DA number is a fast way to sort a long list of sites. It is a poor way to decide which one is worth a link. When a client asks for "DA 50+ links", the useful conversation is about which DA 50 sites have real readers in their field.