Domain Authority: What It Is, What It Isn't

All three scores are weighted estimates of organic ranking strength, calculated from link-graph data (number of referring domains, the authority of those referring domains, link diversity, follow vs nofollow ratios, and various spam-detection factors). Each vendor uses its own crawled link index and its own proprietary algorithm.

• Moz Domain Authority (DA): 0–100 logarithmic; based primarily on Moz's link index and SERP correlation modeling.
• Ahrefs Domain Rating (DR): 0–100 logarithmic; based on Ahrefs's link index, weighted by the DR of linking domains.
• Semrush Authority Score (AS): 0–100; combines Semrush's link data with traffic data and spam signals.

Google has stated repeatedly and publicly (Search Central, John Mueller, Search Liaison across multiple years) that it does not use Moz DA, Ahrefs DR, Semrush AS, or any third-party 'authority' score as a ranking signal. Google has its own internal signals (the descendants of PageRank, plus topical relevance and quality systems) that are not exposed to the public.

When SEO people say 'Google's domain authority,' they are conflating Google's internal authority signals with the third-party scores. The two are loosely correlated (both reward similar link-graph properties) but they are not the same thing.

Despite not being a Google signal, the third-party scores are useful in three legitimate ways.

• Comparative analysis: comparing your DR to a competitor's DR gives you a rough sense of relative link-graph strength. The absolute number matters less than the gap.
• Link-acquisition triage: when evaluating a guest post, sponsorship, or PR opportunity, the linking site's DR gives a quick sense of whether the link is meaningful.
• Tracking your own progress: watching your DR trend over months is a useful proxy for whether your link-building efforts are accumulating.

Treating DA/DR as a ranking factor. (It isn't.) Buying links from sites with high DA but no topical fit. (Google evaluates link relevance, not just authority.) Comparing DR across very different industries. (Industry baselines differ wildly — DR 40 in a niche B2B vertical may be much stronger than DR 60 in a generic consumer category.) Setting OKRs around DA/DR scores. (You're optimizing for a vendor metric, not for actual organic performance.)

Track outcomes, not vendor scores: organic clicks and impressions in Search Console, qualified organic conversions in GA4, share of voice for your priority keyword set, and citation rate in AI Overviews and generative engines. These are all directly tied to business value. DA/DR is at best a leading indicator of these and at worst a distraction from them.