How Domain Authority Is Calculated
Domain authority isn't a metric Google uses directly. It's a third-party approximation created to help SEO practitioners estimate a site's competitive strength. Moz calculates it using machine learning models trained against actual search results, factoring in:
Link profile: The quantity and quality of external sites linking to the domain name
Linking root domains: How many unique websites link to you (more valuable than many links from few sites)
Link quality: Links from high-authority sites carry more weight than links from low-authority sites
Spam score: Signals that indicate manipulative or low-quality link building
The algorithm updates periodically, which means your score can fluctuate even if nothing about your site has changed. A domain authority of 40-50 is considered average. Scores above 60 are strong. Above 80 is exceptional—typically reserved for major brands and established publications.
Domain Authority vs. Page Authority
Domain authority measures the ranking strength of an entire domain. Page authority measures the strength of a single page. A site might have high domain authority overall but individual pages with varying page authority depending on how well-linked each page is.
Both metrics matter. Domain authority gives you a baseline; page authority tells you which specific pages have earned the most trust.
Why Domain Authority Matters for Domain Buyers
When evaluating expired domains or premium domains, domain authority helps you assess whether a domain carries existing SEO value. A domain with established backlinks and a reasonable authority score may give your new site a head start compared to registering a fresh domain name with no history.
However, context matters:
Check the backlink profile: High authority means nothing if the links are spammy or irrelevant to your niche
Look at referring domains: 50 links from one site is less valuable than 50 links from 50 different sites
Consider relevance: A domain with authority in finance won't transfer that advantage to a fitness site
Limitations of Domain Authority
Domain authority is a comparative metric, not an absolute one. It's useful for benchmarking against competitors, but it won't tell you exactly where you'll rank. Google's actual algorithm considers hundreds of factors—including DNS configuration, site speed, and content quality—that Moz can't fully replicate.
Domain Authority vs. Domain Rating (DR)
Domain Authority (DA) and Domain Rating (DR) are the two most commonly referenced authority metrics, but they measure different things:
| Feature | Moz Domain Authority | Ahrefs Domain Rating |
|---|---|---|
| Scale | 1–100 | 1–100 |
| Basis | Linking root domains + link quality + spam signals | Backlink profile strength (how strong linking sites are) |
| Updates | Periodic algorithm updates | Continuously updated |
| Free access | Limited (MozBar extension) | Limited (Ahrefs Webmaster Tools) |
Key differences:
- DA uses machine learning models trained against actual search results, attempting to predict ranking ability
- DR focuses purely on backlink strength — how many unique sites link to you and how strong those sites are
- A site can have DA 45 and DR 65 — the scores often disagree
- Neither is "better" — they measure slightly different things
Other authority metrics:
- Semrush Authority Score — Combines traffic data, backlinks, and spam signals
- Majestic Trust Flow — Measures link quality based on how close your backlinks are to trusted seed sites
- Majestic Citation Flow — Measures link quantity regardless of quality
Use multiple metrics for a more complete picture. No single score tells the full story.
What Is a Good Domain Authority Score?
Domain authority is relative — what's "good" depends on your competitive landscape:
| DA Range | Typical Sites |
|---|---|
| 1–20 | New websites, small personal blogs |
| 21–40 | Established small businesses, niche blogs |
| 41–60 | Popular blogs, mid-size companies, local news |
| 61–80 | Major brands, large publications, authoritative sites |
| 81–100 | Wikipedia, Google, Facebook, major news outlets |
Important context:
- DA is logarithmic — going from 20 to 30 is much easier than going from 70 to 80
- Compare yourself to direct competitors, not to unrelated sites
- A DA of 30 can dominate a niche where competitors are all under 25
- The number itself matters less than your position relative to competitors ranking for your target keywords
How to Improve Domain Authority
Domain authority grows through earning high-quality backlinks over time. There's no shortcut. Effective approaches include:
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Publishing original research or data others want to cite
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Creating tools or resources that attract natural links
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Guest posting on reputable sites in your industry
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Building relationships that lead to editorial mentions
Attempting to manipulate domain authority through link schemes typically backfires. Google's algorithms are designed to detect and penalize artificial link building.
Frequently Asked Questions
What is a good domain authority score?
A domain authority of 40-50 is average. Scores above 60 are considered strong. Above 80 is exceptional and typically reserved for major brands, news organizations, and established publications. New websites usually start with a score around 10-20.
Does Google use domain authority?
No. Domain authority is a third-party metric created by Moz, not an official Google ranking factor. Google uses its own internal signals (including something similar to the original PageRank) but doesn't share specific scores publicly.
How long does it take to improve domain authority?
Improving domain authority typically takes months to years. It requires consistently earning quality backlinks from reputable sites. There are no quick fixes—sustainable growth comes from creating valuable content that others naturally want to reference and link to.
Can domain authority go down?
Yes. Domain authority can decrease if you lose backlinks, if linking sites lose their own authority, if Moz updates their algorithm, or if competing sites grow faster. The score is relative, so even maintaining your link profile doesn't guarantee a stable score.
Is domain authority the same as domain rating?
No. Domain authority (DA) is Moz's metric, while domain rating (DR) is Ahrefs' equivalent. Both measure backlink-based authority on a 1-100 scale, but they use different algorithms. A site might have DA 45 and DR 55—the scores often differ.