What Is a Link Score, and How Is It Calculated by Different SEO Tools and Platforms?


A link score is a numerical value assigned to a website or webpage indicating the quality and strength of its backlinks. Various SEO tools and platforms use algorithms to calculate this score based on factors such as the number of backlinks, the quality of linking domains, and the relevance of the links. Here's an in-depth breakdown of how major SEO tools determine link scores.

A link score, also known as "link authority" or "link equity," measures the influence and credibility a website or webpage gains from its inbound links. These scores are pivotal in search engine optimization (SEO) as they often correlate with higher search engine rankings.

Moz: Domain Authority (DA) and Page Authority (PA)

Moz's Domain Authority (DA) and Page Authority (PA) are popular metrics for evaluating link strength:

  • Domain Authority (DA): It ranges from 1 to 100, predicting how well a website will rank on search engine result pages (SERPs). The calculation involves over 40 factors, including the number and quality of inbound links, and the MozRank and MozTrust metrics. You can learn more about DA on Moz's official page.
  • Page Authority (PA): Similar to DA, PA predicts the potential ranking of a single webpage. It uses the same suite of factors as DA but is restricted to the page level. Detailed information is available at Moz's PA guide.

Ahrefs: Domain Rating (DR) and URL Rating (UR)

Ahrefs employs Domain Rating (DR) and URL Rating (UR) metrics for link evaluation:

  • Domain Rating (DR): This metric quantifies the overall backlink profile strength of a website on a scale of 1 to 100. It considers the quality and quantity of external backlinks. More details can be found on Ahrefs' DR blog post.
  • URL Rating (UR): UR assesses the backlink profile of a specific webpage, also on a scale of 1 to 100. It takes into account both the quantity and quality of inbound links. Insightful information is available at Understanding UR by Ahrefs.

SEMrush: Authority Score

SEMrush uses a unified Authority Score to evaluate domain reputation:

  • Authority Score: This composite metric, calculated on a 100-point scale, considers the quantity and quality of backlinks, organic search traffic, and other trust signals. The precise methodology is explained in SEMrush’s guide on Authority Score.

Majestic: Trust Flow (TF) and Citation Flow (CF)

Majestic provides Trust Flow (TF) and Citation Flow (CF) metrics:

  • Trust Flow (TF): This score measures the quality of links pointing to a site, derived from a manual review of seed sites and their upstream links. Explore more about TF at Majestic's Flow Metrics blog.
  • Citation Flow (CF): This metric assesses the quantity of links to a site, regardless of their quality. High CF does not necessarily mean authoritative links, which is why it's often used in conjunction with TF. Detailed documentation is available on Majestic’s glossary.


Link scores, while differing across various SEO platforms, fundamentally aim to quantify the strength of a website or webpage’s backlink profile. Understanding these metrics and their calculation methodologies can significantly aid in SEO strategy formulation and implementation, ultimately leading to improved search engine rankings.