Page Authority is a metric used to estimate the probability of a specific web page ranking in search engine results pages (SERPs). This metric is not used by Google and does not always provide an accurate estimate of ranking ability. Understanding its shortcomings can help better understand when and where to use it—and when and where to ignore it completely.
Page Authority (PA) is a metric developed by Moz SEO
Used to predict how well a specific web page will rank in search engine results pages (SERPs)
Based on the Moz web index and not used by Google as a ranking factor
Doesn’t always provide accurate estimates of ranking power
Can be manipulated to reflect artificially high scores
Page Authority (PA) is a score developed by Moz that predicts how well a specific page will rank on search engine result pages (SERP). Page Authority scores range from one to 100, with higher scores corresponding to a greater ability to rank.
This metric is calculated through consideration of nearly 40 different metrics—but ultimately is most influenced by the number and quality of backlinks. PA is useful to help better understand how competitors are ranking, the potential benefit of certain backlinks, and to predict how likely a page is to rank in the SERPs. There are major issues with PA and knowing when to ignore it entirely is an essential skill any SEO should have.
How Page Authority is Calculated
Page Authority is calculated using machine learning algorithms which take into account more than 40 unique factors. This includes things like inbound backlinks, Pay-Level-Domain (PLD) presence, and total referring domains. As noted by Moz: “The best way to influence a page’s Authority is to improve its link profile.”
Note how they say “improve its link profile” not “build more backlinks.” This means that blasting a webpage isn’t guaranteed to boost Page Authority. However, at least in my experience, voluminous backlink profiles lend to higher DA and PA scores.
Moz uses what’s known as Machine Learning to calculate PA and DA scores. This is a very in-vogue field of computer science that simulates the way our brains associate information. Where traditional computer algorithms look more like recipes or formula—machine learning is much more abstract. Below is an example of how each might approach the problem:
Traditional Algorithm: Divide the total number of backlinks by the total referring domains.
Machine Learning Algorithm: Look at all the data for every website and build a statistical model of which pages are more likely to rank #1.
It’s a bit like magic. For a deeper look into some of the ways Google (as well as others) use Machine Learning check out this article. There are definitely some downsides.
Page Authority Controversy
Over the years, critics have argued that Domain Authority and Page Authority have done more harm than good. This argument is based on the calculation of PA & DA not being something that Google actually uses.
It’s like asking a coworker to rate your job performance—they can take a guess but the only opinion that actually matters is that of the boss. In the case of DA & PA: Moz is the coworker and Google is the boss.
Google doesn’t use Page Authority or Domain Authority as part of their algorithm. It’s not their data. To illustrate this point; John Mueller (Google Trends Analyst) offered a very cheeky response in a Reddit AMA where the topic of PA & DA was brought up:
Domain Authority vs. Page Authority
Domain Authority and Page Authority are very similar. The difference is that Domain Authority (DA) calculates a rating for an entire domain whereas Page Authority is specific to a single page.
Moz’s calculation of Page Authority does not account for any on-page factors such as content quality or keyword relevancy. For this reason, the Page Authority metric is best to be used as a broadly descriptive metric—with the highest predictive relevancy being found in comparison to similar web pages.
For example, two websites of near-or-equal Domain Authority—each with an article about a similar keyword topic—will likely have their ranking ability separated by overall Page Authority. The one with the higher Page Authority, in many cases, will outrank the one with a lower score.
It’s kind of like saying; out of two cars with the same engine—the one with the most fuel will be able to travel the farthest. This type of basic insight can be useful in planning a content strategy—whether you’re working on a multinational website or your personal blog.
Page Authority Helps Explain SERPs
Page Authority can be useful, especially when considered alongside Domain Authority. It can help predict which web pages will outrank others and also help to explain why. For example, Page Authority can be used to spot the most valuable backlinks for a website.
If one website has a backlink from a powerful website with high Domain Authority—such as a CNN, MSNBC, TechCrunch, or BBC—it may still get outranked by a website that has a backlink with from a lesser DA source, but with higher PA.
Good Link: DA—80, PA—5
Better Link: DA 65, PA—30
A link from an article with a DA score of 80 and a PA score of 5 will be a valuable asset to any backlink profile. However, it may not offer as much overall power as a link with a DA of 65 and a PA of 30. It’s a bit more complicated than simply adding the two together and seeing which has the biggest overall number—but that’s kind of how it works. Below is a quick illustration of how these metrics can help predict rankings out in the wild:
Example: “Most Comfortable Shoes”
This keyword search term is definitely product-focused but the SERP has a mixed bag of content types. Generally speaking, this SERP seems to have a considerable amount of opportunity—illustrated by the somewhat odd presence of non-product pages. Below you’ll find an overview of how the Moz Page Authority Metric can help to explain this particular SERP.
Kuru Footwear is a very niche-focused website that is all about shoes. Their backlink profile is almost entirely shoe-related, and their site seems to have been well-optimized for the keyword “Most Comfortable Shoes” and similar variations.
While their overall Domain Authority is somewhat on the low-end of things—their Page Authority is very solid. In this situation, Page Authority can help explain how Kuru Footwear is outranking more powerful domains.
Macy’s is ranking with an internal page for the keyword term “Most Comfortable Shoes” with a much higher domain authority than the Kuru Footwear website, but an almost non-existent Page Authority.
Large eCommerce websites commonly rank like this as a by-product of their overall Domain Authority. Their top-level pages have a lot of links, maybe even their main category pages, but more long-tail sections of the website simply aren’t often prioritized.
Note: Moz sometimes returns different Page Authority scores for subdomains of websites—such as www.macys.com vs. macys.com. At the time of writing, both versions of this url were checked and found to return the same PA value of “1”.
Page Authority Doesn’t Always Help
This metric is a powerful way to make statements like Macy’s needs to focus on building links directly to shoe pages. However, this metric should only ever be used as a general guideline. There are many occasions in which it only tells such a small portion of the story that it’s pretty much useless. Below is one such case where Moz’s Beginners SEO Guide outranks the Wikipedia SEO page for “Search Engine Optimization,” while having less powerful overall metrics.
Moz’s Beginner’s SEO Guide
One of the most popular guides to SEO is provided by the Moz SEO website under the title of Beginner’s SEO Guide—pretty explanatory right? It’s conceivable that many people looking to find out more about SEO; what it is, how it’s used, and where it all began might be interested in this page. Moz has a very authoritative website, and this page is also immensely linked to and has a robust amount of Page Authority.
Wikipedia’s Search Engine Optimization Page
Wikipedia’s page for Search Engine Optimization is a broad discussion of SEO and many related aspects such as White Hat vs. Black Hat techniques, and how it’s applied in modern marketing strategies. Wikipedia has the maximum amount of page authority possible, coming in at an even 100. Surprisingly, this page also has a larger amount of overall Page Authority as well, likely accounted for by a large number of backlinks.
Page Authority can help make short work of batch analysis. I think it gets overvalued by many SEOs I speak with but I also believe it has its place. My best advice is to not get caught up obsessing over Page Authority or Domain Authority when analyzing competitors. Look at the type of content being posted, the backlinks being earned, and any notable UX/UI differences.