What is domain authority in SEO, and what it is not

Domain authority is a score from 1 to 100, created by the SEO software company Moz, that predicts how likely a whole website is to rank in search results compared with other sites. It is built mainly from the link graph: how many other domains link to yours and how strong those domains are. It is a third party estimate, not a Google metric. Google does not publish a domain level authority score and has said repeatedly that it has no such single site wide score in its ranking systems. Domain authority is useful for one job, comparing sites against each other quickly, and misleading when treated as a target.

This page explains what the score measures, how to read it, what the equivalent scores from other tools are, and which work genuinely strengthens a site. For page level ranking work on individual queries, that is on page and content territory.

Where the number comes from

Moz calculates domain authority from its own crawl of the web. The main inputs are the number of distinct domains linking to a site and the strength of those linking domains, scored recursively, so a link from a widely linked site counts for more than a link from an unlinked one. The output is put on a logarithmic scale from 1 to 100 and calibrated against observed search results.

Three consequences follow from that design, and they explain most confusion about the metric:

• It is relative, not absolute. The scale is fitted so that few sites sit near 100. Moving from 20 to 30 is a far smaller achievement than moving from 70 to 80.
• It can fall without you doing anything wrong. If the index grows, or other sites gain links faster than yours, your score drops while your site is unchanged.
• It knows only what its crawler found. Each tool has a different index, which is why the same site scores differently in each one.

The equivalent scores, side by side

Metric	Tool	Scope	Built mainly from
Domain Authority	Moz	Whole domain	Linking root domains and their strength
Page Authority	Moz	Single URL	Links to that URL
Domain Rating	Ahrefs	Whole domain	Linking domains, weighted by their own rating
Authority Score	Semrush	Whole domain	Links, organic traffic and spam signals
Domain Trust	Various	Whole domain	Link quality and trust propagation

They are not interchangeable. Comparing a Moz score for one site with an Ahrefs score for another tells you nothing. Pick one tool and use it consistently.

What Google actually uses

Google's public position is consistent: there is no single domain wide authority score in its ranking systems. What it does use includes links as one signal among many, page level relevance to the query, and site wide quality assessments that are not expressed as one public number. Google's own guidance is that nobody can guarantee a number one ranking, and it names the promise of a specific position as a warning sign when choosing an agency.

So the honest framing is this: a higher domain authority score usually correlates with a site that ranks well, because strong sites attract links. Correlation runs from the site's strength to the score, not from the score to the rankings. Raising the number for its own sake changes nothing.

How to use the score well

There are four jobs it does properly.

• Judging a link opportunity. When you have a list of sites that might link to you, the score is a fast first filter. Check relevance and real traffic before acting on it.
• Sizing up a competitor set. If the pages ranking for your target query sit far above you, the realistic plan is longer tail queries first rather than a head term now.
• Vetting a domain purchase. Along with historic traffic and a manual look at the link profile, it helps spot a domain whose strength is artificial.
• Tracking direction over quarters. Looked at over a year, with the same tool, a rising line is a reasonable sign that your digital public relations and content work are earning links.

Two things it is not for: a target in a contract, and a monthly key performance indicator. Report organic revenue, qualified leads, non brand sessions and visibility on your query set instead.

How to strengthen the site, which is what the score reflects

The work below raises both rankings and, over time, the score. Do it in this order.

Earn links to assets worth citing. Original data, a calculator, a genuinely useful template, or a clear explainer in a field where the existing explanations are poor. One widely cited asset outperforms fifty guest posts.

Do digital public relations with a real angle. Survey your own customer base, publish the method, and offer journalists a number nobody else has. Comment services and expert sourcing requests are a reliable route for a small team.

Fix the links you already have. Find pages that return 404 but still have external links and redirect them to the right page. Reclaim mentions of your brand that were never linked.

Tidy your internal links. Authority moves through a site. Link from your strongest pages to the ones that need help, with descriptive anchor text.

Keep the profile clean. Paid link schemes, private blog networks and mass directory submissions are against Google's spam policies and put the site at risk.

Be patient on the number. Link growth shows up in a crawler's index weeks after a link goes live, and the score updates on the tool's own cycle.

The domain authority in SEO questions worth an answer

What is a good domain authority score?

Good is relative to your competition. Compare yourself with the sites ranking on page one for the queries you want, using one tool, and set your expectations from that gap rather than from a universal number. A local service business and a national publisher live on different parts of the scale.

Is domain authority a Google ranking factor?

No. It is a Moz metric calculated outside Google. Links, which are a large input to the score, are one of many signals Google uses, which is why the score tracks ranking strength without being a cause of it.

How long does it take to increase domain authority?

Expect movement over quarters rather than weeks, because new links take time to be crawled, indexed and counted, and the score is recalculated on the tool's schedule. Measure link acquisition monthly and the score quarterly.

Why did my domain authority drop?

The common causes are recalibration of the index, competitors gaining links faster, lost links from sites that removed or redirected a page, and a change in the tool's model. Check your referring domain count over the same period. If that is stable or rising, the site is fine.

Does domain authority matter for local business?

Less than people assume. Local results are driven heavily by proximity, the Google Business Profile, reviews, and consistent listings. Links still help, and a handful of relevant local links does more for a plumber than chasing a score.

A score that no tool reports yet

Authority scores describe how a site stands in a link graph that search engines crawl. A growing share of buying questions now goes to an assistant, which returns one answer naming two or three companies. ChatGPT, Gemini, Perplexity, Claude and Google's AI Overviews each decide that independently, cite different sources, and publish no score or ranking to track, so a domain authority figure says nothing about whether you get named.

Checking it is straightforward. Ask the question a customer would ask, keep your own brand name out of the prompt so the answer is not steered, and record who is named and which pages are cited. AI Knows Us runs those checks across the assistants and shows the sources behind each answer.