Moz and Domain Authority: Who Calculates It and What It Misses

Domain Authority is a product of Moz, the SEO software company founded by Rand Fishkin. It is calculated by neither Google nor any neutral web-standards body: it is a proprietary metric that Moz sells as part of the Moz Pro suite and also exposes, in limited free form, through its own website and the MozBar browser extension.

The raw material behind it is Moz's own link index, called Link Explorer. It is an independent web crawler that builds its own map of which pages link to which, running in parallel to Google's index but with no access to it. That matters because the size and freshness of that index directly determine which links Moz can actually "see" pointing at a domain. A new site, or one with few links picked up by Moz's crawler, can show a low DA simply because Link Explorer hasn't found those links yet, not because Google considers the site weak.

Put differently: anyone checking a domain's DA in MozBar or an agency report is looking at one private company's judgment, based on its own crawl of the web, not a figure pulled from Google or confirmed by Google.

The metric became popular mainly because MozBar shows it directly when browsing any page, with no need to look anything up. That made DA a quick shorthand in sales conversations, link-building pitches, and agency reports, well before comparable scores from competitors were available. That convenience explains much of its reach, but says nothing about how accurate the number actually is.

Moz describes DA as a machine learning model trained to predict the likelihood that a domain will rank well against others in search results, based on link data. In its own documentation, Moz states the score draws on "dozens of factors" from Link Explorer, including the number of linking root domains, the quality of those links, and other signals that correlate with rankings observed across thousands of real search results. That also includes Spam Score, another Moz-built metric that penalizes link profiles showing typical manipulation patterns, such as overly exact-match anchor text or links from low-quality networks.

In March 2019, Moz shipped a revision known as Domain Authority 2.0, replacing the previous linear model with one retrained from the ground up on a new dataset, with the stated goal of bringing the score closer to how Google's actual algorithm behaves. Moz summed it up at the time this way: the update was meant to "better mimic how Google weights domains," so the number would be a more reliable reference when comparing a site against its competitors.

What Moz does not publish is the exact weight of each individual factor inside the model, or the full formula that combines those dozens of signals into a final number. That part is Moz's intellectual property and isn't documented publicly, which is standard for any third-party metric built on a trained model: the input categories get explained, the closed algorithm behind them doesn't. There's also no fixed public schedule for when the index gets recrawled or the model retrained. What stays constant is that it doesn't happen in real time but in cycles, so a DA value pulled today reflects a Moz index snapshot that is already somewhat dated.

Moz applies the same modeling logic to a sibling metric, Page Authority (PA), which scores a single URL instead of an entire domain. Both share the same underlying opacity: Moz explains what kinds of signals go in, not how either one weighs them internally.

DA is not a Google ranking factor. That's not a loose interpretation: Moz's own documentation recommends using the score "as a comparative metric rather than an absolute one" and states it has no direct effect on search results. On Google's side, John Mueller, then Search Advocate on the Search team, answered in a Reddit AMA on the r/TechSEO subreddit in March 2018, responding to SEO consultant Bill Hartzer's question about whether Google used anything like a "domain authority score" internally. His answer, documented in Ahrefs' support articles, was that Google has "nothing like a website authority score." The original Reddit thread could not be verified directly for this research, since automated access to it is blocked, so this quote rests on a secondary source rather than the primary one.

DA also isn't a measurement in the strict sense, it's a statistical prediction. The description Moz itself uses, a "model trained to predict the likelihood of ranking," makes that clear. Nothing gets measured as fact; a relative probability gets estimated from past link patterns.

And a high DA guarantees nothing. A domain can carry a high DA score and still fail to rank for a specific query, because actual Google rankings depend on relevance, search intent, content quality, and hundreds of other signals that DA neither evaluates nor claims to evaluate.

DA works reasonably well as a rough comparison between similar domains, measured with the same tool and at close-together dates. If two competitors in the same industry show DA 20 and DA 55, it's reasonable to assume the second has, overall, a more built-out link profile. The number is also useful for tracking a domain's own progress over time, provided the same tool is used consistently, so that changes reflect real movement rather than differences in methodology between providers.

It stops being useful, and turns actively misleading, the moment it gets presented as an absolute value with no context. A DA of 40 doesn't mean the same thing in every industry: in a narrow niche it can be an outstanding score, while in a mature market like banking or travel, where leaders often sit above DA 80, that same 40 lags far behind. Comparing the DA of a small niche online store with that of an international news outlet delivers no useful information, because the two compete in entirely different link ecosystems.

Nor is DA suited to predicting a specific search position, or to replacing a site's own performance data: Search Console and real organic traffic say far more about how a site is actually doing in Google than any figure calculated by an outside provider working from its own index.

It's also worth not mistaking correlation for cause. Several independent analyses from the SEO community show some tendency for domains with a high DA to also rank better. That's because both outcomes depend on the same underlying thing, a strong, naturally built link profile, not because a high DA score itself causes better positions. Anyone chasing the DA number alone, without improving actual relevance and content quality, won't see anything for it in Google.

The most common mix-up is with Ahrefs' Domain Rating (DR). Both scores run on a 0-to-100 scale and both get presented as an indicator of link strength, which leads plenty of people to treat them as interchangeable. They aren't: two different companies, two different crawlers, two different link indexes, and two different proprietary formulas. A DA of 40 and a DR of 40 on the same domain are coincidence, not equivalence, because each index has crawled a different slice of the web. Something similar applies to Majestic's Trust Flow and Citation Flow, another provider running its own crawler that shares neither an index nor a formula with Moz.

Something similar applies to Semrush's Authority Score, another 0-to-100 metric built on that tool's own methodology and data. An academic study published in July 2023 in the journal Profesional de la información, by Reyes-Lillo, Morales-Vargas, and Rovira, analyzed thousands of domains and found a high correlation, above 0.9, between the scores from Moz, Semrush, and Ahrefs. That correlation shows the three tools tend to agree on which domains are strong and which aren't. It doesn't put them on the same scale: they remain three distinct proprietary models, and the same number appearing in two of them doesn't necessarily describe the same link profile.

The underlying mistake behind all of these mix-ups is assuming any of these numbers comes from Google, or that Google consumes them in some way. DA is not PageRank, nor a public version of it: PageRank is an internal Google concept with its own history and its own logic, one Google has never exposed as a lookup-able number equivalent to Moz's DA.

Moz didn't start out as a metrics company. It began in November 2004 as a blog called SEOmoz, run by Rand Fishkin and his mother, Gillian Muessig. Fishkin worked as a web designer in Seattle and was frustrated with how opaque SEO was at the time: reliable information about how search engines actually worked was hard to come by, so he started publishing his own notes online, half journal, half tutorial, covering links, keywords, and site structure.

For its first few years, SEOmoz was mostly a consulting shop that moved from project to project, with the blog as its shopfront. The shift toward software came between 2007 and 2008: the company shipped its first suite of analytics products and, in September 2007, closed a $1.1 million funding round from Ignition Partners and Curious Office. Between 2008 and 2011, revenue grew from $1.5 million to $11.4 million. In May 2013, the company rebranded as Moz.

Domain Authority wasn't the founding project. It arrived later, as one metric among several inside a company that had started life as an educational blog and consultancy. In 2021, Moz was acquired by iContact Marketing Corp, a subsidiary of J2 Global.

Moz has been rolling out AI visibility features inside Moz Pro throughout 2025 and 2026, under the name AI Visibility. The dashboard lets you enter a brand, define what counts as a mention, and add up to three competitors, then tracks whether that brand shows up in ChatGPT and Gemini responses, where in the response it appears, and how its share of mentions moves against competitors over time. As of August 2026, the feature was still in open beta on several plans, per Moz Pro's own pricing page.

The rollout has come in documented stages via Moz's public changelog: June 2026 brought tracking for Google's AI Mode, under the heading "Three engines. One dashboard: Introducing AI Mode tracking." Citation data followed later that month, and August 2026 saw a "Moz Data MCP Server" appear in beta, a way for AI agents to pull Moz data directly. Moz.com could not be fetched directly for this research, automated access was blocked, so these dates come from Moz's public changelog as tracked by a third-party monitoring service, not from the primary source viewed firsthand.

Per The Next Web, Moz, which has tracked search behavior for over twenty years, positions its AI SEO Toolkit as a way to "close the gap between traditional SEO and LLM visibility" without forcing agencies onto a separate platform or a second login.

Moz works well as a fast, cheap entry point into link-based SEO. MozBar has sat installed in thousands of browsers for over a decade, so checking a page's DA takes almost no extra effort. Spam Score adds a useful layer for spotting manipulation patterns in a link profile, and two decades of Moz's educational content remains a solid reference point for anyone starting out in SEO.

Where Moz falls short is transparency around its own calculation: as covered above, neither the exact weight of each factor nor the full DA 2.0 formula is public, and the score depends on what Link Explorer has actually crawled, not on what exists on a domain in reality. That can leave DA lagging behind a domain's real link profile, especially for new sites or ones with recent link growth.

On AI visibility, Moz arrived later than the other two tools covered in this series: Ahrefs opened Brand Radar in beta back in March 2025 and now covers seven AI platforms, and Semrush officially launched its AI Toolkit on March 4, 2025. Moz's equivalent feature was still in open beta as of August 2026 and covered fewer platforms, ChatGPT, Gemini, and AI Mode, without the citation depth or custom prompt tracking the other two already offer.