Domain Authority (DA) is a score from 1 to 100, created by the SEO software company Moz, that estimates how likely a whole website is to rank in search results compared with other sites. It is not a Google metric, and Google does not use it.
How Domain Authority works
Moz crawls the web to build its own index of links. Its model looks at the links pointing to each domain, especially how many distinct websites link to it and how strong those sites are, and produces a score designed to correlate with ranking ability. Moz trains the model by comparing its link data against real search results.
The scale is logarithmic, so moving from 20 to 30 is far easier than moving from 70 to 80. Scores are also relative: when Moz’s index grows or its model changes, many sites’ scores shift together even though nothing about the sites changed. A sister metric, Page Authority, applies the same idea to individual URLs.
Why it matters
DA is useful as a quick comparison. When you look at the sites ranking for a phrase you want, their scores give a rough sense of how much link strength you may be up against. When you weigh up a potential link source, a very low DA can point to a site with little standing, though not always.
What it cannot do is explain your rankings. Google has its own systems, built on far more data than any third-party tool can see, and pays no attention to Moz’s numbers. In local search especially, relevance, proximity and reviews often outweigh raw link strength, so a Walthamstow electrician with a modest DA can outrank national directories with much higher scores for searches in their area.
Common mistakes
- Treating DA as a goal. Raising DA for its own sake leads to chasing links that impress the tool rather than customers or Google.
- Buying links priced by DA. Link sellers often price placements by DA. High-DA sites with no real audience are common in these lists, and some scores are artificially inflated.
- Swapping DA and DR as if they were the same. They are different calculations from different link indexes, so always compare like with like.
- Panicking when it drops. A fall in DA often reflects a Moz model update or the loss of low-value links, with no change in Google traffic at all.
How to act on it
Use DA alongside other checks, never on its own. Before pursuing a link, look at the site itself: does it publish genuine content for a real audience, does it receive organic traffic according to a tool such as Ahrefs or Semrush, and is it relevant to your customers? A regional business magazine with a modest DA and a real readership in your area is a better target than an unrelated high-DA blog.
For your own site, track the outcomes that matter, such as rankings for priority terms, organic traffic and enquiries, and treat DA as background. If you want link strength to grow, the dependable route is earning links from more distinct, relevant referring domains. That is the focus of my link building work, which judges each opportunity on relevance and audience rather than one score. For how Ahrefs approaches the same question with different data, see Domain Rating.