Search Engine Optimization (SEO) professionals use a series of different metrics to help better understand ranking factors. Two of the most widely-used metrics are Page Authority (PA) and Domain Authority (DA). These numbers help predict which web pages will rank for keywords and which domains will outrank others. Knowing how to apply these two concepts makes any SEO strategy more effective.
SEO isn’t about any single number or any single strategy. Ranking websites involve many different considerations such as creating quality content, earning quality backlinks, and ensuring on-page presentation is done by current SEO best-practice. The list is long, and always growing longer. The key to building successful websites is to integrate concepts such as Domain Authority and Page Authority into every aspect of SEO and marketing strategy.
Moz is a professional-grade SEO toolkit that provides the Domain Authority (DA) and Page Authority (PA) SEO metrics. Moz has undergone some changes over the past few years and offers these metrics through different services now. They have historically been provided by the Open Site Explorer and the MozBar, but today are most readily-accessible through the Link Explorer and MozBar tools.
The MozBar requires that you generate a set of API credentials (free or premium) and download the browser extension. Moz offers an in-depth guide for getting the MozBar setup properly. The MozBar is, by far, the most popular way to access this data. It’s free to use, easy to use, and helps analyze sites on the fly while searching in Google. This tool is especially useful for gauging the competition of different keyword SERPs and, in my opinion, is largely responsible for Moz’s popularity.
The Link Explorer tool is comparable to Semrush’s Domain Overview or Ahrefs’ Site Explorer. This tool provides much more data than just Domain Authority and is Moz’s answer to Semrush and Ahrefs. The Moz Link Explorer also reports backlink data, organic keyword positions, historical metrics, anchor text profiles, and several other useful data points. This tool is useful, but in my opinion nowhere near as robust as the Semrush or Ahrefs SEO tools.
Having to juggle consideration for such a medley of factors, SEO professionals often rely on holistic metrics to help gauge site quality and SEO power. Kind of like IQ scores—predictive, but often lacking a lot of context. Just like I know plenty of smart people with IQs that would likely measure as average, I have also seen plenty of websites ranking well while having only mediocre metrics. Google doesn’t share their ranking algorithms publicly.
The metrics used to predict SEO factors are just that—predictions. Metrics such as Domain Authority and Page Authority, offered by Moz, are just estimations. In my experience, these metrics are useful in giving broad estimates but often come up short when used on a site-by-site basis. That’s to say, DA and PA can help filter out a couple dozen quality sites from a list of ten thousand but can’t usually predict which of those sites will rank best for certain keywords.
In my opinion, the practical application of metrics from companies such as Moz, Semrush, Ahrefs, or Majestic is found in large-scale analysis. These metrics are useful in helping to pick out higher-quality websites, or web pages, from lists of hundreds or thousands. Relying on them for individual site analysis will often overlook a lot of important context. After all, they’re just numbers.
On the other hand, keeping the concept of these types of metrics in mind while applying SEO strategy can be powerful. For example, recognizing that building higher Domain Authority will also help rank individual pages is important. It can help better understand how one should structure homepages, category pages, and other top-level pages in such a way that boosts the SEO of deeper pages.
Domain Authority (DA) is an SEO metric used by the Moz SEO service to predict the overall SEO power of a domain. It predicts how likely a website is to rank for anything, taking into account factors such as backlinks, the total number of referring domains, and “dozens” of other factors. It’s scored on a logarithmic scale of 0-100, which means that growing a sites’ DA from 0 to 30 is much easier than growing it from 30 to 40.
Machine learning algorithms calculate Domain Authority scores by analyzing tons of other websites and their keyword ranking positions. This means that Domain Authority when used as a metric, is relative to other websites. This means having a higher DA score doesn’t also mean your website will start ranking better. It means your website is more likely to start ranking better if your sites’ DA score is higher than your competitors’ DA score. It’s all pretty much guesswork honestly.
The Domain Authority metric used to be provided by Moz through their Open Site Explorer (OSE) tool. They’ve restructured the company considerably in recent years, and Domain Authority is now reported through their Link Explorer tool, as well as their browser add-on MozBar. Free accounts are allowed to run 10 free Link Explorer lookups per month through the Link Explorer tool and an indefinite amount via the MozBar.
When used as an SEO metric, Domain Authority offers a quick analysis of large numbers of websites and web pages. When applied as a concept to overall SEO strategy, it can help create a more effective website structure and give a competitive edge against SERP competitors. The concept is simple; by taking actions to increase the overall authority of a website domain one can also effectively increase the overall authority of specific pages. That’s to say, getting a link to your homepage can help inner pages rank as well. This is one of the fundamental concepts of tree-based SEO website structure.
Page Authority is very similar to Domain Authority in that it is an SEO metric used to predict ranking positions. The difference is that, rather than predicting the SEO power of an entire website, Page Authority is used to predict the SEO power of a single web page.
Just like Domain Authority, Page Authority is calculated by applying machine-learning algorithms to large datasets. This takes into account “dozens” of ranking factors to come up with a calculated estimate of how strong a competitor a single page will be. Just like Domain Authority, Page Authority is also scored on a logarithmic scale of 0-100.
Page Authority scores are accessible in the Link Explorer and MozBar tools. When using the Link Explorer to analyze an entire domain, one will find that only the Domain Authority score is given. When entering a specific URL address to a single page, however, the “exact page” filter will be applied and provide both metrics.
Recognizing that Page Authority improves the likelihood of any single webpage to outrank the competition is a critical concept to master in SEO. This helps explain why building backlinks to specific pages, even if they’re already ranking decently, is a powerful strategy. Having internal links and external links to a single webpage passes along PageRank and contextual relevancy. Both of these are powerful ranking factors that will improve keyword rankings.
Domain Authority vs. Page Authority
Knowing what Domain Authority and Page Authority will help improve one’s overall SEO strategy, assuming one applies the concepts. They’re useful in predicting the competition for certain keywords, how competitive a domain is likely to be for any keywords and also useful for buying and selling websites. Understanding the differences between the two can help identify opportunity in the SERPs. For example, these concepts help to recognize that ranking for a parent-level keyword may not be feasible but ranking for a long-tail variation would be easy! There are three common types of DA/PA combinations to watch for, and each has a different meaning.
Type 1: High DA/Low PA
Authoritative websites like Wikipedia, CNN, or Amazon will often have single pages rank well for keywords without having much SEO done. That’s to say, Amazon might rank number one for the keyword beard trimmer without having any backlinks and only having minimal on-page content.
Their overwhelmingly high Domain Authority is channeled into all their single web pages as well. When there isn’t a lot of competitor web pages with optimization for specific keywords, I find that larger websites tend to float to the tops of the SERP simply because they have high overall Domain Authority.
This phenomenon is kind of like Google saying “we don’t know who has the best answer to this question so we’ll take the answer from someone we know gives good answers to other questions.”
Type 2: Low DA/High PA
Websites that are much lesser known than international websites can still rank very well, even for competitive keywords. This is an example of how niche websites can outrank Wikipedia for specific topics but Wikipedia still ranks well for millions of topics.
Websites with lower overall domain authority can build high Page Authority by earning backlinks and creating a great user experience. These conditions help explain how a DA: 30 PA: 50 webpages will almost always outrank a DA: 90 PA: 10 web pages. This has a lot to do with relevancy in my opinion but is also most directly related to backlinks. It’s why Wayfair and Rooms-to-Go outrank Amazon for furniture-related keywords even though Amazon sells furniture as well.
Type 3: High DA/High PA
Web pages from popular sites about popular topics are almost always going to end up in this category. These are pages that rank on the first page of the SERPs for keywords like latest news, health insurance, and online banking. These keywords drive such profitable traffic, that tens of millions of dollars are justified in pursuing them. Trying to outrank these pages is usually a fool’s errand.
In many cases, websites that have high DA and high PA for certain pages are still vulnerable to competition for longer-tail keywords. There’s a lot of value placed on relevancy by search engines like Google, and most web pages aren’t going to be the most relevant result for every related keyword. In the wild, this often looks like giant website ranking in the top positions for top-level keyword phrases, while smaller websites are still able to rank well for longer-tail variations.
During one’s keyword research and competitive analysis, if a SERP is full of many pages that have high DA and high PA metrics, it’s often best to find another keyword. There are some exceptions though. SERP features like the Local Pack have allowed smaller websites to compete with international brands. For example, a local credit union could benefit from optimizing their website for keywords like high yield savings account, low-interest loan, or even credit cards. They aren’t going to outrank sites like Bank of America or Wells Fargo in the national organic results but, when Google applies local filters, they can outrank those sites for local searchers.
Domain Authority and Page Authority are two concepts that earned their names by the Moz metrics commonly used by SEO professionals. The balance of SEO power described by these two metrics can be useful in understanding how strong domains can rank by default, how weak domains can outrank strong domains, and how attempting to compete against strong domains for their money keywords is a bad idea. As concepts, Domain Authority and Page Authority are crucial to developing SEO strategies. I don’t personally recommend anyone bother with the Moz metrics anymore, as I believe they’ve become useless for effective competitive analysis.