Domain Authority

Domain Authority is a search engine ranking score developed by Moz that predicts how likely a website is to rank in search engine results pages, calculated on a logarithmic scale from 1 to 100 based on the quantity, quality, and diversity of a site’s backlink profile.

What Domain Authority Means in Practice

Domain Authority (DA) is one of the two most widely referenced third-party authority metrics in SEO, alongside Ahrefs’ Domain Rating. Moz created DA as a predictive metric: it doesn’t measure how well a site ranks today, but how likely it is to rank well given the strength of its backlink profile and other signals. That distinction matters, because it shapes how the metric should (and should not) be used.

DA is calculated using a machine learning model that Moz trains against actual Google search results. The model identifies which link profile characteristics best predict ranking success, then assigns each domain a score. The inputs include the number and authority of linking domains, the relevance of those links, and other proprietary factors that Moz doesn’t fully disclose. The output is a score from 1 to 100, where higher numbers indicate stronger predicted ranking ability.

The logarithmic scale is the most important detail that practitioners misunderstand. Moving from DA 20 to DA 30 is significantly easier than moving from DA 60 to DA 70. At the upper end of the scale, each point requires exponentially more backlink strength. This means that comparing a DA 40 site to a DA 80 site isn’t a 2x gap. It’s closer to an order-of-magnitude difference in backlink profile strength.

In day-to-day SEO work, Domain Authority serves three primary functions. Competitive benchmarking is the first and most common. If your site has a DA of 35 and the top-ranking competitors for your target keywords all have DAs between 55 and 70, that authority gap tells you something important about the investment required to compete. It doesn’t tell you it’s impossible, but it tells you that content quality and on-page optimization alone probably won’t close the gap. You’ll need a deliberate link building strategy.

Link prospecting is the second use case. When evaluating whether a potential linking site is worth pursuing for outreach, DA provides a quick filter. A link from a DA 60 site is generally more valuable than one from a DA 15 site. It’s not the only factor, as relevance and traffic matter too, but it’s a useful first-pass filter when you’re evaluating hundreds of potential link targets.

Progress tracking is the third. Monitoring your own DA over time provides a directional signal about whether your link-building efforts are working. A site that climbs from DA 25 to DA 35 over six months has meaningfully improved its backlink foundation. But DA is a relative metric: Moz continuously recrawls the web and recalibrates scores, so your DA can shift without any change to your own backlink profile. The signal that matters is the long-term trend, not weekly fluctuations.

Where Domain Authority falls short is in specificity. DA is a domain-level metric. It tells you about the overall website, not about individual pages. A site with a DA of 70 might have individual pages with zero backlinks and no authority. Moz offers Page Authority (PA) as a companion metric for page-level evaluation, but most practitioners focus on DA because it’s simpler to benchmark and track.

The other limitation is that DA is a third-party metric, not a Google metric. Google does not use Domain Authority (or any Moz metric) in its ranking algorithm. DA is a proxy that correlates with ranking success because the underlying signals, primarily backlinks, are genuine ranking factors. Treating DA as a direct input to rankings leads to misguided decisions, like chasing high-DA link placements regardless of topical relevance.

Why Domain Authority Matters for Your Marketing

Domain Authority matters because it’s one of the most accessible ways to understand your competitive position in search. If you’re a healthcare group with a DA of 30 competing against hospital systems with DAs of 70+, that gap explains why your content isn’t ranking for high-volume terms even though the content itself is strong. Understanding the authority gap reframes the conversation from “our content isn’t good enough” to “our content needs a stronger authority foundation to compete.”

Moz’s research on ranking factors found that domain-level link authority is among the strongest predictors of ranking performance across their model. The correlation isn’t perfect, as there are plenty of low-DA pages that outrank high-DA competitors for specific queries, but the trend is clear: higher DA correlates with greater organic visibility, especially for competitive, high-volume keywords.

For organizations managing multiple websites or acquiring new digital properties, DA also provides a fast diagnostic. A PE firm evaluating a target company can check the website’s DA in seconds and immediately understand the baseline authority position. We use this routinely during initial audits. A site with a DA under 20 tells us we’re starting with a minimal authority foundation and need to factor significant link-building investment into the growth timeline. A site with a DA of 50+ tells us the authority foundation exists, and we can focus more resources on content and technical optimization.

How Domain Authority Works

Moz calculates Domain Authority using a machine learning model called Domain Authority 2.0, which was overhauled in 2019 to improve accuracy and reduce susceptibility to manipulation. The model uses Moz’s own link index (called Link Explorer) as its primary data source and incorporates dozens of signals, though the exact algorithm is proprietary.

The core inputs include the number of unique root domains linking to the target site, the authority of those linking domains (creating a recursive relationship), the quality and spam scores of the linking sites, and how the target site’s link profile compares to other sites in Moz’s index. Unlike Domain Rating, which focuses almost exclusively on the backlink graph, DA incorporates a predictive model trained on actual search ranking data. This means DA is designed to estimate ranking likelihood, not just measure link profile strength.

The logarithmic scale creates a non-linear scoring curve. Moz’s documentation on Domain Authority explains that DA is best used as a comparative metric rather than an absolute score. A DA of 40 is not twice as “authoritative” as a DA of 20. The effort required to move from 40 to 50 is substantially greater than moving from 20 to 30. Sites at the very top of the scale (DA 90+) include global brands like Google, Facebook, and Wikipedia, with link profiles built over decades.

What distinguishes DA from Domain Rating is the methodology and intended purpose. DA uses Moz’s link index and a machine learning model trained on ranking data, making it a ranking predictor. Domain Rating uses Ahrefs’ link index (which is generally larger) and focuses on raw backlink graph analysis without incorporating ranking predictions. In practice, a site’s DA and DR scores for the same domain will differ, sometimes significantly. Neither is “right.” They’re measuring overlapping but distinct things from different data sets. The best practice is to choose one as your primary benchmark and use it consistently.

Common mistakes include obsessing over small DA changes (a 1-2 point fluctuation usually means nothing), comparing DA across different industries (a DA of 40 in financial services means something different than a DA of 40 for a local restaurant chain), and treating DA as a goal rather than a diagnostic. DA is an input to your analysis, not an output of your strategy. The goal is rankings, traffic, and revenue. DA helps explain why you’re achieving (or not achieving) those outcomes.

External Resources

• Moz’s Domain Authority Guide — Moz’s official documentation on how Domain Authority is calculated, including the DA 2.0 methodology and comparison guidance
• Moz’s Domain Authority Guide — The technical breakdown of Moz’s DA methodology, explaining the machine learning model and how scores are calculated
• Google’s How Search Works — Google’s official explanation of how it discovers, crawls, and ranks pages, providing context for why third-party authority metrics exist
• Ahrefs’ Domain Rating Explained — Ahrefs’ documentation on their competing metric, useful for understanding the differences between DA and DR

Related Resources

• The SEO Metrics Your Leadership Team Actually Cares About — How to translate authority metrics like Domain Authority into business outcomes that leadership teams evaluate
• How Long Does SEO Take to Show Results? — How domain authority gaps affect SEO timelines and what to expect at each stage of growth
• The Ultimate SEO Checklist: A Complete Guide for 2026 — Comprehensive SEO framework that includes off-page authority building in the context of a complete optimization program
• Enterprise SEO: What Makes It Different and How to Get It Right — How domain authority dynamics change at enterprise scale with complex site architectures and multiple subdomains

Related Glossary Terms

• Domain Rating: Ahrefs’ competing metric for measuring backlink profile strength on a 0-100 scale. Domain Rating and Domain Authority measure similar concepts using different methodologies and data sources.
• Backlink: A hyperlink from one website to another. Backlinks are the primary input that Domain Authority evaluates, and the quality and quantity of backlinks directly influence a site’s DA score.
• Link Building: The process of acquiring backlinks from external websites. Link building is the primary activity that drives Domain Authority improvements over time.
• Organic Traffic: Unpaid search engine traffic. Domain Authority correlates with organic traffic potential because stronger authority scores indicate better ranking likelihood for competitive keywords.