What Is Domain Authority?

Domain Authority is a metric developed by Moz, the SEO software company founded by Rand Fishkin. It runs on a 0 to 100 scale and aims to show, in relative terms, how likely a domain is to rank compared with other domains. Google does not calculate this score, nor does any search engine: it comes from Moz's own machine learning model, trained on data from its link index, Link Explorer.

The calculation combines several link-related signals: the number of linking root domains, the quality of those domains, anchor text distribution, and a spam score that penalizes suspicious link profiles. Since March 2019, with the version known as DA 2.0, Moz replaced its earlier linear model with a neural network trained against real Google search results, aiming to correlate better with actual rankings. Even so, it remains a statistical approximation, not a copy of Google's algorithm.

The scale is logarithmic, not linear. Moving from 10 to 20 points is far easier than moving from 70 to 80, because each higher tier requires a disproportionately larger number of quality links. Moz also updates its index periodically, so a DA score from six months ago may no longer match the current one, especially if a domain's link profile, or its competitors', has shifted.

DA became popular partly because it reached the market before most free alternatives, and because browser extensions like MozBar display it the moment you visit any page. That turned it into the go-to shortcut for sizing up a domain in seconds, in sales pitches, outreach proposals, and agency reports. It was never meant to replace a full link analysis, but its convenience meant plenty of people treated it that way.

Moz's index is smaller than Google's, so new domains or ones with few detected links can show a very low DA simply because Moz hasn't crawled enough links to them yet, not because the site is low quality. Moz recrawls its index at intervals, historically every few weeks, which explains why the same domain's DA can shift slightly between two lookups even when nothing relevant changed in its link strategy.

Domain Authority is not a Google ranking factor, and that is not an interpretation: Google has denied it explicitly and repeatedly. In March 2018, John Mueller, Search Advocate at Google, answered a question during a Reddit AMA on r/TechSEO from SEO consultant Bill Hartzer, who asked whether Google used anything similar to a "domain authority score" internally. His answer, documented by Search Engine Journal and in Ahrefs' support documentation, was that Google does not have "anything like a website authority score." Verification note: we could not access the original Reddit thread directly (automated access was blocked), so this quote is confirmed through two independent, matching secondary sources rather than the primary source itself. That statement lines up with the position Google has repeated over the years: there is no internal metric called "domain authority" feeding into the ranking algorithm.

What Google does use are hundreds of its own signals, including internal variants of PageRank at the page and link level, calculated with its own index and its own logic, which does not match Moz's formula or any other provider's. The confusion happens because DA is easy to explain in a meeting, so many SEO teams use it as mental shorthand for "authority," even though Google never validates it or feeds it into anything.

This isn't a one-off either. Whenever a Google spokesperson has been asked directly about Domain Authority, Domain Rating, or any comparable third-party metric, the answer has stayed consistent with the 2018 one. Domain Authority does not appear in any public Search Central guide about ranking factors, nor in the official documentation on how Google Search works.

That said, Domain Authority is not a useless number. It works as a quick relative comparison between domains under the same criteria: if one domain has a DA of 55 and another has a DA of 15, it is reasonable to assume the first has a stronger link profile, as long as both were measured with the same tool at similar points in time. It is also useful for prioritizing link building targets, for example when filtering a list of a hundred sites for outreach and narrowing down to the highest-DA ones first, before checking topical relevance and real traffic.

DA stops being useful when it is treated as an absolute truth or as a direct ranking proxy. It says nothing about the exact position a page will hold for a specific query, because rankings depend on relevance, search intent, content quality, and dozens of other factors that DA does not measure. It is also not directly comparable to Ahrefs' Domain Rating or Semrush's Authority Score: all three use a 0 to 100 scale, but each tool crawls its own link index and runs its own formula. A DA of 40 and a DR of 40 on the same domain is coincidence, not equivalence.

Several independent analyses from the SEO community have found a moderate correlation between high DA and good Google positions, but that correlation is indirect: domains with more quality links tend to have both a higher DA and better ranking chances, without one causing the other. Treating correlation as causation is the most common mistake when this metric ends up in a client report. A practical example: when choosing between two content partnerships, one with a topically well-matched blog at DA 25 and another with an unrelated portal at DA 60, the second isn't automatically the better pick. Relevance carries at least as much weight as the number.

Who actually pays attention to this number also varies. Link building teams and digital PR agencies use it daily as a quick filter in their workflows, while a technical SEO team focused on indexing or Core Web Vitals rarely needs it. If the goal is assessing a domain's overall health, DA is just one piece alongside total link counts, real organic traffic, and visibility for the keywords that matter to the business.

Domain Authority has a sibling metric called Page Authority (PA), which applies the same methodology to individual pages instead of entire domains. Both share Moz's underlying model, but they answer different questions: DA compares whole domains against each other, while PA compares specific pages, for example when deciding which article on the same blog carries the most weight for an internal link pointing at a page you want to rank.

DA also says nothing about the quality of any individual link, only about the aggregate volume. A link profile packed with weak directory listings can still land a mid-range DA, as long as the spam score stays within a reasonable range. Anyone evaluating a domain as a potential link partner should also check the actual link profile instead of relying on this number alone. That matters especially for domains pulling in a conspicuous share of links from a single network or country, something the DA score won't reveal but a manual review catches quickly.

• Use DA only as a relative comparison between similar domains, never as an absolute figure.
• Track DA over time with the same tool, so changes reflect real progress rather than differences between providers' methodologies.
• Cross-check DA against topical relevance and real organic traffic before deciding on a link exchange or partnership.
• Explain to clients and teams that DA is a third-party metric, not a Google data point, to avoid misplaced expectations.
• Check a domain's DA before investing in a link, but treat it as an initial filter, not the only quality criterion.
• Note in reports that DA is a Moz estimate with a lookup date, so it's clear the number can shift with the next index update.

• Selling Domain Authority to a client or manager as a Google ranking factor.
• Comparing one domain's DA to another domain's DR as if they were the same scale.
• Chasing a higher DA number as a goal in itself, instead of earning relevant, quality links.
• Ignoring that Moz recalculates its index periodically, which can move DA without anything changing on the site itself.
• Dismissing a domain with a low DA without checking its real traffic or topical relevance, especially for newer sites with few indexed links so far.
• Presenting DA as a universal benchmark for any industry without comparing it against the client's direct competitors.