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What Is Domain Authority? How the Third-Party SEO Metric Works
Domain Authority (DA) is a third-party metric created by Moz, the SEO software company, that scores a website's likely ability to rank in search results on a scale from 1...
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Domain Authority (DA) is a third-party metric created by Moz, the SEO software company, that scores a website’s likely ability to rank in search results on a scale from 1 to 100. Higher scores indicate a stronger backlink profile relative to other sites in Moz’s index. DA is one of the most widely cited numbers in SEO reporting, but it is also one of the most misunderstood: it is not a Google metric, Google does not calculate it, and Google does not use it to decide rankings.
Understanding what DA actually measures, and what it doesn’t, matters for anyone using it to evaluate a website, a link prospect, or a competitor.
What Domain Authority actually measures
Moz describes Domain Authority as a predictive ranking score built primarily from the strength of a site’s link profile, including the number of linking root domains and the quality of the links pointing to a domain (Moz, “Domain Authority”). The score is generated by a machine-learning model trained to correlate a site’s link signals with how well sites tend to rank across the web. It uses a logarithmic scale, which means it gets progressively harder to gain points as a score climbs. Moving from DA 20 to DA 30 is a meaningfully smaller lift than moving from DA 70 to DA 80, because at the top of the scale a site is competing against the very best-linked domains on the internet.
A few characteristics worth keeping in mind:
- DA is relative, not absolute. It is calculated by comparing a site against the rest of Moz’s link index, so the score can shift over time even if a specific site’s own link profile hasn’t changed, simply because the comparison set changed.
- It is a domain-level score. It does not tell you which specific pages on a site are strong or weak (that is closer to what Page Authority attempts to estimate).
- It is recalculated periodically as Moz’s link index updates, so a site’s DA can fluctuate without anything on that site changing.
- The underlying model itself has been overhauled before, not just the index behind it. In 2019, Moz moved DA from a linear model to a neural-network-based model that also folded in its proprietary Spam Score, a bigger, one-time recalibration that shifted many sites’ scores at once. That kind of model-level change is rarer and different from the routine index refreshes above, but it is the reason long-time DA watchers sometimes see a sharper jump or drop than normal link activity would explain.
Domain Authority is not a Google ranking factor
This is the single most important thing to understand about DA: Google does not use it, has never used it, and has no internal metric that resembles it. Google’s own developer documentation is explicit that third-party SEO tools and the data they produce do not come from Google’s internal systems, and that third-party scores should not be mistaken for actual Google ranking signals (Google Search Central, “Google Search’s guidance on third-party SEO tools & advice”). Moz itself, as the creator of the metric, is similarly direct that Domain Authority was built as a comparative research and benchmarking tool rather than a simulation of Google’s algorithm (Moz, “Domain Authority”).
This distinction matters because DA correlates with rankings without causing them. Sites with strong backlink profiles also tend to be older, more established, more frequently linked to because they publish things people want to cite, and better resourced for technical SEO and content. DA picks up on the link-profile piece of that picture, which is why high-DA sites often do rank well, but the score itself is not an input Google’s ranking systems read. Improving a number on a third-party dashboard does nothing for rankings on its own; the underlying link growth, content quality, and site health that the number is trying to approximate are what matter.
Domain Authority vs. Domain Rating vs. Authority Score
DA is not the only metric of this kind. Ahrefs and Semrush each publish their own proprietary scores that attempt to do something similar, and the three are often confused with one another because they look alike on the surface (a 0 to 100 scale describing “authority”) while being calculated differently and pulling from different link indexes.
| Metric | Vendor | Scale | What it primarily measures |
|---|---|---|---|
| Domain Authority (DA) | Moz | 1-100, logarithmic | Predicted ranking strength based on linking root domains and link quality from Moz's index (<a href="https://moz.com/learn/seo/domain-authority">Moz</a>) |
| Domain Rating (DR) | Ahrefs | 0-100, logarithmic | Strength of a site's backlink profile based on referring domains and how DR is distributed across the domains a site links to, from Ahrefs' index (<a href="https://ahrefs.com/seo/glossary/domain-rating">Ahrefs, "What is Domain Rating?"</a>) |
| Authority Score (AS) | Semrush | 0-100 | Compound score combining backlink signals, estimated organic traffic, and spam-risk signals, from Semrush's index (<a href="https://www.semrush.com/kb/747-authority-score-backlink-scores">Semrush, "What is Authority Score?"</a>) |
Because each tool crawls and indexes the web differently, the same site will often show three different scores across the three platforms, and none of them is “the real one.” They are independent estimates built on different data, different weighting, and in Semrush’s case, additional inputs beyond links. None of them is a Google ranking signal, and a high score on one does not guarantee a comparable score on another.
How to actually use Domain Authority
Used correctly, DA (and its counterparts) are useful comparative tools, not goals. Reasonable uses include:
- Competitive benchmarking. Comparing your DA to a handful of direct competitors gives a rough sense of how your overall link profile stacks up, which is useful context when prioritizing link-building or content investment.
- Prospecting triage. When evaluating a long list of potential link or partnership targets, DA is a fast (if imperfect) first filter for separating well-established sites from very thin ones, before you look closer at relevance and actual traffic.
- Trend tracking. Watching your own DA over months can be one signal, among several, that your link-building efforts are having an effect, alongside referring-domain counts, organic traffic, and rankings for target terms.
What it should not be used for is setting it as an SEO goal in itself (“get our DA to 50”), since that encourages chasing the score directly rather than the underlying link quality and content that the score is trying to estimate.
Manipulation and gaming risks
Because DA correlates with link volume and link-source authority, it can be inflated artificially, at least temporarily, through low-quality link schemes: private blog networks, bulk paid links from low-relevance sites, or directory and forum spam aimed purely at link counts. A site can sometimes push its DA up this way without improving its actual search visibility, because Google’s own systems weigh link relevance, link spam signals, and many factors beyond link counts that third-party metrics don’t fully capture (Google Search Central, “Spam policies for Google Web Search”). A gamed DA score is also fragile: when Moz’s index updates or a manipulative link network gets devalued, an artificially inflated score can drop just as fast as it rose.
The practical takeaway is the same one that applies across SEO metrics: treat DA as a diagnostic instrument, not a destination.
Frequently asked questions
Is a higher Domain Authority always better?
Generally yes, in the sense that it reflects a stronger link profile relative to other sites in Moz’s index, but it is a comparative score, not an absolute one. A DA of 40 might be excellent in a niche where competitors sit around 20, and unremarkable in a competitive national space where competitors sit around 70.
Can I improve my Domain Authority directly?
Not directly. DA moves as a byproduct of earning more (and higher-quality) backlinks and growing your overall link profile relative to the rest of the web. There is no setting to adjust or technical fix that raises DA on its own.
Does Domain Authority predict rankings?
It correlates with rankings in aggregate studies, because both DA and rankings are influenced by similar underlying factors (link profile strength among them), but correlation is not causation, and DA is not one of the inputs Google’s ranking systems actually use.
Why does my Domain Authority change even though I haven’t built any new links?
DA is recalculated against Moz’s evolving link index, so scores can shift up or down simply because the comparison set, or Moz’s crawl of the web, changed, not because anything on your site changed.
Should I report Domain Authority to clients or stakeholders as a success metric?
It can be one supporting data point in a broader report, but it should not stand in for rankings, organic traffic, and conversions, which are the metrics that actually reflect business impact.