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Domain Authority: What It Is And How To Build It

Andi Coombs
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On the surface, Domain Authority (DA) seems pretty simple, right?

What’s better: a DA99 or a DA52?

If you answered DA99, good job...

You were wrong


Because Domain Authority isn’t a grade; it’s a comparative metric. 

It’s only useful when comparing your score to your competitors. And using it in any other way has led many SEOs astray (myself included). 

Let’s try again. 

What’s harder: Moving from DA20 to DA21, or moving from DA80 to DA81?

If you answered the same, congratulations… 

You were wrong again

Because Domain Authority uses a logarithmic scale. High DA is exponentially more difficult to achieve than low-authority DA. A one-point move in the 80s is actually bigger than a one-point move in the 20s. 

Not so simple, huh?

I know—been there. 

Which is why the biggest problem with DA is that it appears super easy to use, so most SEOs don’t explore how it actually works. Consequently, they use it wrong. 

In this article, we’re going to peel back the onion: what is Domain Authority, how is it calculated, what are its limitations, and how can you use it to inform your SEO strategy?

In the end, you’ll know how to use DA to make smarter decisions about building your authority and choosing the right keywords. (And never get a DA pop quiz question wrong again!)

Let’s go!

What is Domain Authority? 

Domain Authority (DA) is a search engine ranking potential score (0-100) invented by Moz that predicts how likely it is for one website to outrank another in search results. The higher the score, the higher likelihood of ranking. 

Domain Authority isn’t a ranking factor itself (e.g. not to be confused with PageRank). But it strongly correlates with rankings. 

For example, a website with DA70 is likely to outrank a website with DA14 for the same keywords

Moz free DA checker
Moz’s Domain Authority Checker (Free) – source

Moz isn’t the only software with their hat in the Domain Authority ring. Majestic, SEMrush, and Ahrefs have their own versions of DA called Flow Metrics (TrustFlow/Citation Flow), Authority Score, and Domain Rating (DR) respectively. 

One difference: Whereas Ahrefs, SEMrush, and Majestic were designed to measure the strength of a domain, MOZ’s DA was specifically designed to predict rankings. No other metric correlates with rankings as well as DA does. In fact, DA correlates with search engine results page (SERP) rankings 6% better than Ahrefs, 35% better than Citation Flow (Majestic), and 18% better than Trust Flow (Majestic). Moz put it to the test.

Moz’s DA compared to competitors
Moz’s DA vs. Majestic’s CF and TF vs. Ahrefs DR – source

How is Domain Authority calculated?

Sophisticated machine learning. 

Essentially, Moz has back-engineered their own algorithm and index (“Link Explorer” formerly OpenSiteExplorer), just like Google’s algorithm and index (though not nearly as sophisticated or big). 

Link Explorer has crawled and indexed over seven trillion pages, 700 million root domains, and 40+ trillion links. 

From that data, Moz uses dozens of factors when calculating DA scores, including social media signals, backlink quality information (AKA backlink profile), and more. But two data points take precedence over the rest:

  1. Linking root domains (unique linking domains) 
  2. Total number of backlinks (AKA inbound links) 

That’s right, DA is a link-based metric that analyzes the quality and quantity of backlinks pointing to a site to predict how well it might rank in SERPs. 

The more often a high-authority linking root domain links to yours, the higher your DA. 

Bonus: Moz has done a fabulous job of handling link manipulation when calculating DA, which means they actively seek to keep link networks/sellers, domain auctions, comment spammers, and private blog networks (PBNs) out of their link index. 

Good Domain Authority vs. Bad Domain Authority 

DA is best used as a comparative metric, not in isolation (it’s not a grade). 

The only “bad DA” is one significantly lower than a competitor’s within the same category and industry. 

For example, is a DA20 bad compared to Amazon’s DA96? Not unless you were walmart.com. 

But if all of your direct competitors have DA70s compared to your DA14, you have work to do. 

That’s because some industries are more link-friendly than others. For example, industries like eCommerce, beauty, and publishing/media attract tons of links compared to industries like nutrition, plumbing, and veterinarian. 

Also, keep in mind that it’s much harder to grow from DA70 to DA80 than it is to grow from DA20 to DA30.

Why? Because DA is scored on a logarithmic scale. That means that the distance between DA75 and DA76 is much greater than the distance between DA20 and DA21. 

Domain authority logarithmic scale
Domain Authority logarithmic scale example - source

A small group of authority sites with massive link profiles occupy the space at the top right (Think: YouTube, Amazon, Apple, Google, Wikipedia). Whereas moving from DA20 to DA30 might require a few thousand links, moving from DA70 to DA80 might require a few hundred thousand links. 

So whatever you do, don’t compare your DA to the likes of YouTube (DA100). You’ll never get there. 

Top 10 DA sites
Top 10 Domain Authority websites – source

Domain Authority vs. Page Authority 

Moz has another link-based metric called page authority (PA). 

Like DA, PA also uses the quality and quantity of linking root domains to predict the likelihood of ranking, only at the page level, not the domain level. 

In most cases, we love PA more than DA when analyzing rankability. That’s because tons of high domain authority websites like YouTube may have gargantuan Domain Authority, but lack the topical expertise at a page level, or be poorly optimized at the page level. 

For example, YouTube may have over 21M links which gives them a DA100, but do they have a page that talks about cadmium plating a barrel piston from a Boeing 747? And if they do, has it acquired any links of its own? 

Another example: When you search for “stimulus check” on Google, the IRS ranks #1. Not surprising, but if you take a closer look, it’s not because their DA is high (their page one competitors have high DA too, in some cases higher); it’s because of their high PA (over 300K+ links to one page). 

High PA examples
The IRS ranks this page not because of high DA, but because of high PA

Domain Authority vs. keyword difficulty 

If both DA and PA are supposed to measure ranking potential, and thus help you determine your chances of ranking, then what is keyword difficulty supposed to measure?

What is keyword difficulty?

It’s a score that keyword research tools use to predict how difficult it will be to rank for a certain keyword. 

Keyword difficulty scores according to different tools
Keyword difficulty scores from various SEO tools

Sounds like DA or PA, right? Kinda. 

Think of it this way: Keyword difficulty is like the average page authority of all page one rankings. For example, if the keyword difficulty of the search term “SEO” is 77/100, that means the average page authority of the top ten sites that rank for it is roughly 77. If you want to outrank them, you’ll need a page authority of 77 too. 

So whereas DA and PA measure authority, keyword difficulty aggregates that authority into a difficulty score (higher scores being more difficult). 

Want to learn more about keyword difficulty? We wrote an entire article on it here: Keyword Difficulty (Why it Matters & How to Measure it For Free)

Limitations of Domain Authority

While DA is a great predictor of rankability (and useful to any SEO), it’s not without its flaws.

Third-party metric (i.e. not a Google metric)

DA uses 40+ factors (largely link-related) to predict rankings, whereas Google uses 200+ factors to rank websites. DA can’t possibly match the complexity of Google, which is why increasing it doesn’t always correlate with higher rankings.

DA doesn’t measure content quality, search intent, on-page SEO, or the relevance of links (i.e. links from industry-specific websites or not). All of which are significant ranking factors. It’s not uncommon to see a lower PA/DA website outrank a higher one because it was better optimized. 

Limited index

Google crawls nearly every page on the web. Moz’s Link Explorer crawls seven trillion. That’s a lot, but certainly not every page on the web. This means the number of linking root domains isn’t 100% accurate. 

Relative metric:

If a website that links to your website receives a billion new links, it’s going to change your DA (and everyone it links to) also. This means DA improvements need to be checked against your competitors always. Did your DA drop/increase because of something you did? Or because of something someone else did? Hard to tell at first glance. 

Does Domain Authority matter?

Despite its shortcomings, DA is still a useful metric for any SEO. 

Compare DA with your competitors

If your DA drops or increases significantly more, it may indicate a drastic change in your (or their) link profile. 

Compare DA historically

If your DA drops over time, that means the number of linking root domains has dropped as well. Best to get to work. If it increases, then you’ve improved your ranking strength, which means your SEO strategy is working. Do more of it. Either way, measuring historical DA is a great way to measure link performance over time.

Prioritize outreach

Maybe you’re researching guest blogging opportunities, link building outreach, media partnerships, or purchasing a domain. DA can measure the value of those links. You’d certainly want to consider more than just DA, but DA can help you make a better decision. For example, you would want to prioritize a link from a DA80 website over a DA10 website. 

Think more strategically

Yes, DA is just a prediction of your ranking potential. But a pretty damn good one. If your website has a DA14 but all your competitors who rank for a specific keyword have DA80, you don’t have sufficient authority to outrank them. Could you imagine not knowing that ahead of time? Yeesh. 

Tools to check Domain Authority 

Whether Moz, Ahrefs, Semrush, or Majestic, each tool has a feature to enter a URL and find their version of a domain’s authority. 

Our favorite tool is Moz because it’s the OG and most accurate predictor and because they have a browser extension (called Mozbar) that shows PA/DA directly from within SERPs (which makes comparison easy). Download the browser extension here

Domain Authority in Mozbar: 

Mozbar extension
Download Mozbar, and when you type in a Google search, you’ll see DA directly below snippets.

Domain Rating in Ahrefs: 

Domain rating in Ahrefs
Domain Rating in Ahrefs - source

Authority Score in SEMRush: 

AS in Semrush
AS in Semrush - source 

TrustFlow and CitationFlow in Majestic 

TF and CF in Majestic
TF and CF in Majestic - source

How to Build Domain Authority

Don’t obsess over DA. Like we mentioned, it’s an indicator of your ranking potential, not an actual ranking factor (increasing it won’t make Google happier). If your goal is to increase your DA score for the sake of it, stop right now. 

However, if you want to increase your website’s actual authority, then use historical DA as a metric to measure progress, proceed. 

Good news: authority isn’t a secret.

There’s a reason why domain authority scores from different SEO tools rely so heavily on links. Because they matter most.

Graph of rankings correlating with domains
Number or referring domains correlates with rankings most - source

I wish we had more to say here, but we don’t. Simple: increase the amount of high-authority websites that link to your website and you’ll increase your real domain authority in the eyes of Google. Consequently, your DA score will shoot up too. 

You can’t fake real authority: the only way to increase linking root domains is to produce high-quality content worth linking to. Period. 

And remember, since DA is scored on a logarithmic scale, securing a link from a DA80 website is exponentially more valuable toward building your authority than securing one from a DA20 website. 

This should go without saying, but do your best to remove (or avoid) spammy links to your website.

What are spammy links? Low-quality links from websites are often penalized or banned for shady link practices like link selling or blackhat SEO. 

Note: Low-quality doesn’t necessarily mean low authority (i.e. low DA). You would expect to find a healthy dose of low-DA websites linking to yours; that’s normal. But you wouldn’t expect to find a high dose of poor-quality (thin content, spammy link profile, not relevant to your niche, etc.) websites linking to yours. 

Moz uses a proprietary metric called Spam Score which influences your DA score too. Your spam score is based on the number of links pointing to your website that resemble links from websites that are often penalized or banned by Google. Moz uses 27 important factors to determine this score. 

Moz’s spam score
Moz’s spam score

If your domain has a high spam score (30%+), this doesn't necessarily mean your website is spammy; it just means you have too many poor-quality websites linking to yours. 

If that’s the case, open up Google’s free Search Console, navigate to links (bottom left in menu), view your backlinks and linking root domains, then check the DA of each link manually to see which are bad and which are good. Remove bad ones. 

Check backlinks in Google’s Search Console
Check your backlinks for free in Google’s Search Console

The best backlinks aren’t just links from high-authority websites; they’re links that drive traffic from your target audience. Not only do they increase rankings and subsequent organic traffic, but they increase awareness with real buyers, which can lead to direct sales. 

Plus, don’t you think Google likely analyzes link traffic, too? Of course. 

Link traffic is a sign of relevance. Relevance is the cornerstone of Google’s algorithm. 

Wrapping up 

If you break down SEO into two parts, you get relevance and authority. 

In SEO circles, we refer to this as on-page SEO and off-page SEO

Relevance means that everything on a specific webpage, from content to on-page optimization to user experience, satisfies the searcher’s intent and expectations. 

Authority means that other websites recognize your credibility as a relevant authority, so they link to you as a source. 

You need both. 

But without a Domain Authority score, it makes much of your off-page authority building harder. This is why DA will forever be a critical SEO metric

So use it often during keyword research and link building, but use it how it was intended: as a comparative authority metric. 

“Wow- my DA is 52. I’m good!” doesn’t mean anything. 

DA is best used to determine your relative competitiveness. That is, what is your ranking potential compared to other websites competing for certain keywords, and what does that potential tell you about your realistic chances of ranking?

And always remember: DA is not a ranking factor; it’s a ranking indicator. Big difference. 

Chapter 3:
Off-Page SEO

What You’ll Learn: There are more ranking factors than just what’s on a website. Here’s where you’ll learn about what impacts SEO that’s outside your direct control.

Chapter 4:
Technical SEO

What You’ll Learn: Your SEO depends on robots. Read this chapter to make sure robots can easily read through all your amazing content, otherwise, you’ll never show up.

Chapter 5:
SEO Strategy

What You’ll Learn: The websites at the top of the SERP are there because they have a solid content strategy. Learn how to create an SEO strategy that works for you.