Domain Authority vs Domain Rating: what each score measures, and why Google uses neither

• Domain Authority (DA) is Moz's score, from 1 to 100. It comes from a machine learning model built mostly on links, and includes signals about link quality and spam.
• Domain Rating (DR) is Ahrefs' score, from 0 to 100. It is purely about links: followed links from unique domains, with each linking site's strength shared among the sites it links to.
• Both are relative and not linear. Going from 70 to 80 is far harder than going from 20 to 30, and your score can fall because other sites grew.
• Google uses neither. It has its own link analysis, which it still calls PageRank, and it ranks pages rather than handing out a score per domain.
• Use them to compare. Your site against competitors, or one possible link source against another. Never as a target in their own right.

They share a structure. Each one starts from a crawl of the web, its own and no one else's, works out which sites link to which, and squeezes the result onto a 100-point scale. The differences are in what gets counted and how hard each one tries to discount links that look manipulative.

Ahrefs is unusually open about DR. Its help page describes it as the strength of a site's backlink profile compared to the others in Ahrefs' database, and its own explanation of the calculation sets out a few rules:

• Only followed links count. Links marked nofollow do not raise DR.
• Only the first link from each domain counts. A hundred links from one site count once.
• A linking site's strength is shared among everything it links to. A site that links to three others passes each a third. A site that links to a million passes each a millionth.
• Nothing else goes in. No traffic, no domain age, no brand. Ahrefs says DR is purely link-based and does not account for backlink spam.

The third rule is the one that changes how you think about links:

Site A, DR 10links to 3 sites

Your site is one of three. It gets a third of what Site A passes on.

Site B, DR 80links to 1,000,000 sites

Your site is one of a million. It gets a millionth of what Site B passes on.

In Ahrefs' own example, the link from the small site can do more for your DR than the link from the big one.

This is why a link from a small, selective site can do more than one from a big site that links to everyone. It also fits what I saw in my catalogue, where the free directories mostly sit low on the scale: many of them link out to thousands of listings, so whatever strength they have is spread very thin.

Ahrefs puts the result on a logarithmic scale. Its example: the gap between DR 70 and 71 is much bigger than the gap between DR 20 and 21. Each point near the top takes far more links than a point near the bottom.

Moz's Domain Authority comes from a machine learning model rather than a formula. Moz's own explanation says it uses dozens of factors, starting with the number of linking root domains and the quality of those links. On 5 March 2019 Moz replaced the old model with Domain Authority 2.0, which brought in Moz's Spam Score and patterns of link quality, and many sites' scores moved overnight. Moz's Russ Jones called it a dramatic change at the time.

Two things follow from building a score that way:

• DA is harder to reason about. You can work out roughly why your DR moved. With DA, the model weighs things in ways Moz does not publish.
• DA tries to discount spam. DR, by Ahrefs' own account, does not. So the two are most likely to disagree about sites with a lot of low-quality links.

Moz's scale is not linear either. Its explanation says it is easier to take a score from 20 to 30 than from 70 to 80, and that new sites start at 1.

Because each score comes from a different crawl, built with different rules. Moz and Ahrefs do not see the same links, do not count them the same way, and do not squeeze the result onto 100 points in the same way. A site can be DR 40 and DA 30, or the other way round, and both can be right by their own method.

One small illustration: on 13 October 2026, Ahrefs' own Website Authority Checker page used two example scores, ahrefs.com at DR 88 and moz.com at DR 91. By Ahrefs' measure, Moz's site has the stronger backlinks.

The practical rule is to never compare a DA with a DR. Pick one tool, and compare every site with that tool's number.

Both companies say it outright. Ahrefs: think of DR as a relative term. When a DR 100 site gets more links, it cannot become DR 101, so the scale stretches and everyone below gets pushed down. Moz gives the same example for DA: if Facebook.com gained a billion new links, other sites' DA would drop.

So a falling score does not always mean something went wrong. Before worrying, check three things:

• Did you actually lose links? Look at the referring domains count, not the score.
• Did the sites linking to you change? A linking site that starts linking to far more sites, or loses links of its own, passes on less.
• Did the tool change? Moz's 2019 model change moved scores across the web without any site doing anything.

The simplest reason is that they are not Google's. Each is an estimate built by a company that does not run Google Search, from a crawl Google did not make. Google has its own crawl, its own link graph and its own systems for deciding which links to trust.

The longer reason is that Google does not work in domain scores the way these tools do. A few points from Google's own people and documentation:

PageRank is the part that confuses people. It is the link analysis Google was founded on, patented in 2001, and for years Google showed a public score for it in its toolbar. Google switched that off in 2016, and told Search Engine Land at the time that it still uses PageRank internally. Its ranking systems guide says PageRank has evolved a lot and is still part of its core ranking systems. DA and DR are outside attempts at something similar: one public number per site, in the spirit of the old toolbar score. They are not a window into the real one.

There is one honest complication. In May 2024, internal Google documentation leaked, and it mentioned an attribute called siteAuthority. Google confirmed the documents were real and warned against drawing conclusions from out-of-context or outdated information. Mike King, who analysed the leak, wrote that nobody knows how the measure is computed or used. So Google may well have site-level signals of its own, and its own guide says as much. Nothing shows any of them resembles Moz's or Ahrefs' scores, and there is no way to see one from the outside.

The vendors' own advice is good here. Moz says there is no universal good or average DA, and to compare against competitors in your niche. Ahrefs says a DR is good if it is higher than or comparable to similar sites, and not to focus your efforts on growing the number. Semrush says its score is best used for comparing domains, not for judging good or bad on an absolute scale.

Where the scores are useful:

• Sizing up competition. If every page ranking for a search is on a site with DR 70 or more, and yours is DR 15, you know what you are up against.
• Choosing between link sources. Two possible places to write a guest post, same audience: the score is a fair tie-breaker.
• Watching your own trend. The same tool, the same site, over months. The direction matters more than the number.

Where they mislead:

• As a target. Raising DR by collecting links that do nothing else is the pattern Google's spam policy describes. The score goes up and nothing else does.
• As a price. Sites that sell guest posts often price them by DR. A high DR site that links out to everyone, or has no real readers, is still a bad place for your link.
• As proof of quality. A score made only of links cannot tell you whether anyone reads a site. Look at the site itself before you look at its number.

Domain Authority and Domain Rating are two companies' estimates of how strong a site's backlinks are. They are built from different crawls in different ways, so they disagree, and both are relative, so they move even when you do not. Google uses neither. It has its own link analysis and has said it has no overall domain authority score.

Use one of them, consistently, to compare your site with the sites you compete with, and to choose between places to get links. Do not compare a DA with a DR, do not pay for a link because of its number, and do not treat a falling score as a penalty. For your own site, Search Console's Links report is free and is Google's own view, even if it does not give you a score.