Domain authority is one of the most-cited metrics in SEO, and also one of the most misunderstood. People treat a DA score like it's a direct ranking factor search engines use — it isn't. It's a third-party estimate, and understanding what it actually measures (and doesn't) changes how you should use it.
This guide explains what domain authority is, how it's estimated, how it differs from similar metrics like domain rating, and how to use it usefully without over-relying on a single number.
We'll also cover the common misconceptions that lead people to chase a higher DA score in ways that don't actually improve real search performance.
By the end, you should be able to look at a DA score, or any similar third-party metric, and know exactly what it's telling you — and just as importantly, what it isn't.
What Is Domain Authority?
Domain authority (DA) is a third-party metric, developed by Moz, that estimates how likely a website is to rank in search results on a logarithmic 1-to-100 scale. It's calculated using a range of factors, primarily the quantity and quality of a site's backlink profile, and is designed to give SEO professionals a rough, comparative benchmark rather than a precise prediction.
It's important to be clear about what DA is not: it's not a metric search engines themselves use or calculate, and it has no direct effect on your actual rankings. It's a modeled estimate built by a third-party tool, useful for comparison, not a score search engines are watching.
The confusion is understandable, since DA is genuinely useful and widely discussed as if it were an official ranking factor. The distinction matters in practice: a site could have a mediocre DA and still rank extremely well for its target keywords if its content, relevance, and technical SEO are strong, because the actual ranking algorithm considers far more than what DA models.
Why Domain Authority Matters
It's a useful comparative benchmark
DA is most valuable when comparing your own site's trajectory over time, or comparing your site against direct competitors, rather than as an absolute measure of quality.
It's a common shorthand in the SEO industry
Whether or not it's a perfect metric, DA is widely referenced in link building conversations, vendor pitches, and competitive research — understanding it helps you participate in those conversations knowledgeably.
It correlates loosely with backlink strength
Since backlinks are the primary input, DA gives a rough sense of a site's overall backlink profile strength, even though it isn't a precise or complete picture.
Misusing it can lead to bad decisions
Chasing DA as a goal in itself — instead of using it as one signal among many — can lead to buying low-quality links from artificially inflated domains that don't actually help real search performance.
Clients and stakeholders often ask about it directly
Even if you personally treat DA as a rough signal, clients, managers, and partners frequently reference it directly, so being able to explain it clearly and accurately is a genuinely practical skill.
How Domain Authority Is Calculated
While the exact algorithm is proprietary, the general approach is understood well enough to explain at a conceptual level.
Step 1: The tool crawls and indexes a large portion of the web
Moz's Link Explorer, which powers DA, maintains its own independent index of web pages and the links between them, separate from any search engine's own index.
Step 2: Backlink data gets aggregated per domain
The tool counts the number of unique linking root domains and evaluates their own relative strength, since a link from a stronger domain contributes more than one from a weaker one.
Linking domain diversity: A wider variety of unique domains linking to a site tends to increase its DA more than a large number of links concentrated on just a few domains.
Link quality weighting: Links from domains that themselves have strong backlink profiles carry more weight in the calculation than links from weak or low-authority domains.
Example: A single link from a well-established, high-authority publication can move a site's DA more than dozens of links from small, low-authority blogs combined.
Step 3: The result is normalized on a logarithmic scale
Because the scale is logarithmic, moving from 20 to 30 is meaningfully easier than moving from 70 to 80 — each additional point at the high end represents a much larger relative gain in link strength.
Step 4: The score updates periodically
DA isn't calculated in real time — it's recalculated on a regular schedule as the underlying index updates, so recent changes to your backlink profile take some time to show up.
Step 5: The formula gets refined over time
Moz periodically adjusts the underlying model to improve how well it correlates with actual ranking performance, which means a site's DA can shift even without any change to its own backlink profile, simply because the calculation method itself was updated.
Domain Authority vs. Similar Metrics
Domain Authority (Moz)
Best For: General benchmarking and competitive comparison within the SEO community, given its widespread adoption and name recognition.
Watch Out For: Treating it as a precise or absolute measure — it's a comparative estimate, not a guaranteed predictor of ranking ability.
Domain Rating (Ahrefs)
Best For: A similar comparative purpose to DA, calculated with Ahrefs' own independent index and methodology.
Watch Out For: DA and DR scores for the same site are rarely identical, since each tool crawls and weighs links differently — comparing a DA score to a DR score directly isn't meaningful.
Authority Score (Semrush)
Best For: Another comparative option, incorporating backlink data alongside some additional organic traffic signals.
Watch Out For: Like DA and DR, it's a proprietary estimate specific to that tool's own index and formula.
Page-level metrics (like Page Authority)
Best For: Evaluating the ranking potential of an individual page rather than an entire domain, which is often more useful for specific link building decisions.
Watch Out For: Assuming a strong domain-level score guarantees every individual page on that domain is equally strong — it doesn't.
Best Practices for Using Domain Authority
Use it for trend tracking, not absolute judgment
Watch how your own DA changes over months rather than fixating on the exact current number.
Compare within the same tool
Only compare DA scores to other DA scores, DR to other DR scores, and so on — cross-tool comparisons aren't meaningful since each uses a different scale and methodology.
Prioritize relevance over a target DA number
A moderate-DA link from a highly relevant site is often more valuable for real-world SEO than a high-DA link from an unrelated one.
Combine DA with actual traffic and ranking data
A site's DA alone doesn't tell you whether it's actually ranking or getting real traffic — cross-reference it with other signals for a fuller picture.
Don't let DA drive link-buying decisions
Chasing a specific DA number by purchasing links from artificially inflated domains is a common and risky mistake — see Google's link scheme guidelines for why this can backfire.
Check DA alongside relevant page-level metrics
When evaluating a specific link opportunity, look at both the domain-level score and, where available, page-level authority for the exact page that would link to you.
Common Mistakes to Avoid
Treating DA as an official search engine metric
Search engines don't calculate or use DA directly — it's a third-party estimate designed to correlate with, not replace, actual ranking factors.
Comparing DA and DR as if they're the same scale
Because each tool uses a different index and formula, a DA of 40 and a DR of 40 for the same site don't represent the same thing.
Ignoring relevance in favor of a high DA number
A link from a high-DA but completely unrelated site is often worth less in practice than a moderate-DA link from a genuinely relevant one.
Obsessing over small fluctuations
DA can shift slightly between updates for reasons unrelated to your own site's activity — focus on the longer-term trend instead of every small change.
Frequently Asked Questions
What is a good domain authority score?
It depends heavily on your niche and competitors. Compare your DA to sites actually ranking for your target keywords rather than aiming for an arbitrary number.
How can I increase my domain authority?
Build genuinely relevant, high-quality backlinks over time, keep your technical SEO solid, and maintain consistent, credible content — there's no shortcut that bypasses real link quality.
Is domain rating better than domain authority?
Neither is objectively "better" — they're different tools' independent estimates of a similar underlying concept, each useful within its own ecosystem.
Does domain authority directly affect my search rankings?
No. It's a third-party estimate correlated with ranking-relevant factors like backlink strength, but search engines don't use DA itself in their ranking algorithms.
Why did my domain authority score suddenly change?
Scores update periodically as the underlying index refreshes, and can shift due to changes in your own backlink profile or recalculations affecting the broader index.
Can a new website have a high domain authority?
It's uncommon but possible if the site quickly earns links from genuinely strong, relevant domains. For most new sites, DA starts low and grows gradually alongside a real backlink profile.
Key Takeaways
- Domain authority is a third-party estimate of ranking potential, not a metric search engines calculate or use directly.
- It's most useful for tracking trends over time and comparative benchmarking against competitors.
- DA, DR, and Authority Score are all different, tool-specific metrics that shouldn't be compared directly to each other.
- Relevance matters more than a high DA number when evaluating a potential backlink.
- Focus on genuine link quality and relevance rather than chasing a specific DA target.
Building genuinely relevant links is what actually moves metrics like domain authority over time — ZeroSEO's Backlink Exchange can help you find relevant peer sites to link with, and you can sign up to get started. For a deeper technical explanation of how these metrics are calculated, Moz's own documentation is the primary source.