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.

Introduction

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 Pro Pricing Chart

Moz offers a professional SEO toolkit, which features the rampant use of the Domain Authority and Page Authority metrics.

MOZ

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.

NOTE: I don’t use Moz DA and PA metrics for any of my SEO analysis and no longer regard them as valuable metrics for competitive analysis.

MozBar

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.

MozBar Screenshot

The MozBar browser extension for Chrome features quick report data for analyzing sites on the fly.

Link Explorer

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.

Moz Link Explorer tool

The Moz Link Explorer tool provides DA, PA, and other useful SEO metrics.

Predictive Numbers

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.

Moz metrics comparision

Moz metrics aren’t always useful in competitive analysis.

Practical Application

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

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.

Link Explorer Domain Authority

Link Explorer shows top-level Domain Authority metrics

Technical Information

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.

Accessing Data

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.

Conceptual Application

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

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.

Page Authority Link Explorer

Page Authority predicts the overall SEO power of single URLs

Technical Information

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.

Accessing Data

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.

Conceptual Application

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.

Related: Long Tail: How Niches Can Specialize Your Site for Success

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.

High DA Low PA

Pages from domains with high Domain Authority often rank when there isn’t strong competition.

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.

Low DA High PA

Sites with lower Domain Authority but can still rank when specific URLs have high Page Authority

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.

High DA High PA

High Authority websites with high Authority pages are hard to outrank.

Competitor Analysis

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.

MozBar SERP

MozBar enables users to quickly compare search results pages by DA, PA, and several other metrics

Closing Thoughts

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.