Authority Score.

Authority Score is Semrush's proprietary metric that estimates the overall SEO strength of a domain or page on a scale of 0 to 100. It is a composite metric that weighs three factors: the quality and quantity of backlinks pointing to the domain; organic search traffic (as a proxy for real-world usage and Google's assessment of quality); and a spam or toxicity factor that penalises manipulative link profiles. It serves a similar purpose to Ahrefs' Domain Rating and Moz's Domain Authority.

Authority Score vs Domain Rating vs Domain Authority

All three are third-party metrics attempting to approximate Google's internal PageRank signal — none of them are used by Google directly. Ahrefs' Domain Rating is almost purely backlink-based (referring domain count weighted by their DR). Moz's Domain Authority combines link metrics with spam analysis. Semrush's Authority Score adds organic traffic as a third variable, making it potentially more holistic but also more variable when traffic fluctuates.

How to Use Authority Score Practically

Authority Score is most useful as a relative comparison tool: evaluating link building prospects (is this site worth pursuing?), benchmarking your domain against competitors, and tracking the directional growth of your own domain's authority over time. Do not treat exact scores as ground truth — a site with Authority Score 45 is not precisely twice as powerful as one with 22. The score's value is in relative ranking and trend direction, not absolute magnitude.