Domain authority is one of the most referenced—and most misunderstood—metrics in SEO. Marketers use it to evaluate link-building prospects, benchmark competitor strength, and report on site health. But domain authority is a third-party metric, not a Google signal, and treating it as an absolute measure of SEO performance leads to poor decisions. Understanding what it actually measures, how it is calculated, and where it fits in a broader link strategy is essential for using it correctly.
What Domain Authority and Domain Rating Actually Are
Domain Authority (DA) is a metric created by Moz. Domain Rating (DR) is a similar metric from Ahrefs. Both attempt to predict how well a domain is likely to rank in search engine results, using a logarithmic scale from 0 to 100. Higher scores indicate a stronger backlink profile, but neither metric is used by Google in its ranking algorithm.
These metrics exist because Google’s original PageRank score—which was the gold standard for link authority measurement—was made public for many years and was eventually hidden from the public API. Third-party tools developed their own proxies to fill the gap. DA and DR are both reasonable approximations of a site’s overall link strength, but they measure different things using different methodologies and will often produce different scores for the same domain.
How Moz and Ahrefs Calculate Their Scores
Moz calculates Domain Authority using a machine learning model that incorporates the quantity and quality of linking root domains, the MozRank and MozTrust of those links, and how that profile correlates with actual rankings in Moz’s dataset. The score is recalibrated regularly, which means a site’s DA can change even if nothing has changed about its actual link profile—because the broader web has changed around it.
Ahrefs calculates Domain Rating based primarily on the quantity and quality of unique referring domains, weighted by those domains’ own DR scores. The algorithm is logarithmic: moving from DR 20 to DR 30 is much easier than moving from DR 70 to DR 80, because the sites already scoring at the high end have exceptionally strong link profiles that are difficult to match.
The Difference Between Domain Authority and Google’s PageRank
Google’s PageRank algorithm evaluates links as votes of confidence, where a link from a high-authority page passes more value than a link from a low-authority page. While Google has confirmed it still uses a version of PageRank internally, the public PageRank score was retired in 2016.
The key distinction is that Google evaluates authority at the page level, not just the domain level. A link from a low-DA domain to a highly relevant, well-linked page can pass meaningful authority. Conversely, a link from a high-DA domain buried on a deeply nested page with no inbound links passes very little. Domain authority metrics do not fully capture this page-level nuance, which is why using them as the only filter for link prospects is insufficient.
Why Domain Authority Matters for Link Building
Despite its limitations, DA and DR remain useful as a relative signal when evaluating link-building opportunities. A link from a DR 60 domain is generally more valuable than a link from a DR 15 domain, all else being equal. These metrics provide a fast, scalable way to filter prospecting lists when you are evaluating hundreds of potential link sources.
Use DA/DR as a floor, not a ceiling. A minimum threshold (e.g., DR 30+) eliminates obvious spam and low-quality sites from link prospecting. But above that floor, prioritize topical relevance, traffic quality, and editorial standards over raw score. A DR 35 industry publication that your target audience actually reads is more valuable than a DR 60 aggregator site with minimal traffic and no topical alignment.
How to Improve Domain Authority Over Time
Improving DA or DR is a byproduct of improving your actual link profile—it is not a goal in itself. Tactics that move the needle include:
- Earning links from high-authority referring domains through original research, data studies, egobait campaigns, and digital PR
- Increasing the number of unique referring domains, since both metrics weight diversity highly
- Removing or disavowing toxic links that may be suppressing your score
- Building internal link equity to ensure your best pages receive maximum page-level authority from your existing link profile
Why Domain Authority Is a Relative, Not Absolute, Metric
A DA of 40 means different things in different industries. In some niches, DA 40 is above average; in others, it is well below the competitive threshold for ranking on page one. Always benchmark DA and DR against your actual competitors for target keywords, not against a universal standard. Competitor analysis—not absolute score—should drive your link-building investment decisions.
Conclusion
Domain authority is a useful tool in the right context: as a relative benchmark, a prospecting filter, and a rough gauge of competitive link strength. It is not a Google ranking factor, and optimizing for DA as a goal rather than a byproduct leads to misallocated effort. Build links that drive real authority signals—topical relevance, editorial quality, and referring domain diversity—and the score will follow. Need help with your digital strategy? Contact WebPresence today.