What is Domain Authority and Page Authority

In search engine optimization, measuring authority is one of the ways to understand how competitive a website or webpage might be. Since Google does not share its ranking signals directly, marketers rely on third-party metrics to estimate strength. Two of the most commonly used measures are Domain Authority (DA) and Page Authority (PA). Both were introduced by Moz and have become standard references in the SEO industry. To fully understand these metrics, it helps to look at their history, how they are calculated, and how they should be used.

A Brief History of Authority Metrics

In the early years of Google, the company introduced PageRank, an algorithm that used links as votes of trust. Websites with more high-quality backlinks tended to rank better. For a while, Google even displayed a PageRank score in the browser toolbar, which made it easy for anyone to check how strong a website was. However, Google eventually stopped updating the public PageRank scores because people started manipulating links to artificially inflate rankings.

With the disappearance of PageRank data, SEO professionals needed another way to measure authority. This is when Moz created Domain Authority and Page Authority. These metrics were designed to predict the likelihood of ranking in search engines using machine learning models and large link indexes. Since then, they have become a common way to evaluate websites when planning SEO strategies.

What is Domain Authority

Domain Authority is a score developed by Moz that predicts how well an entire domain is likely to perform in search results. The score ranges from 1 to 100, with higher numbers indicating a stronger potential to rank. Domain Authority looks at the overall backlink profile of a site, including the number and quality of referring domains.

For example, a new blog might have a DA of 5 or 10, while a large publication like The New York Times might have a DA above 90. Higher DA sites are generally more trusted and have an easier time ranking for competitive keywords. However, DA is not a ranking factor used by Google. It is simply a comparative metric created by Moz to help SEOs gauge website strength.

What is Page Authority

Page Authority is similar to Domain Authority but it measures the strength of a single page rather than the entire domain. Like DA, it is scored from 1 to 100. A page with more high-quality backlinks pointing directly to it will typically have higher PA.

This makes Page Authority particularly useful when analyzing individual pieces of content. For example, a blog post with a PA of 40 may rank better for its target keyword than another page with a PA of 20, even if they are on the same domain. Marketers often use PA to evaluate which pages are performing well and which need more promotion.

How Moz Calculates DA and PA

Moz uses a machine learning model that takes into account a wide range of link-related factors. The system looks at how many websites link to a domain or page, the quality of those sites, and the overall link structure. The result is a score that is relative, meaning it works best when comparing one site to another.

The scores also fluctuate whenever Moz updates its index or changes its model. For example, if a competitor gains many new backlinks, your DA could drop even if you did nothing wrong. This is why it is important to see DA and PA as comparative rather than absolute.

Why Domain Authority and Page Authority Matter

DA and PA matter because they provide a quick way to benchmark against competitors. If you are trying to rank for a keyword, looking at the DA and PA of the top-ranking pages can give you an idea of how much effort will be needed.

They are also useful when evaluating backlink opportunities. If a site with a high DA links to you, it usually provides more value than a link from a low DA site. Similarly, checking the PA of the page linking to you can help determine the strength of that link.

These metrics can also guide outreach and promotion strategies. For example, if you know your competitors have a DA of 60 and your site is at 30, you may need to build stronger backlinks and publish more authoritative content to close the gap.

Limitations of DA and PA

Although widely used, DA and PA are not official ranking factors. Google has stated many times that it does not use these metrics. Instead, they are predictions built by Moz to mimic search engine behavior.

This means you should never rely only on DA or PA when making SEO decisions. A site with low DA can still rank if it provides excellent content and targets less competitive keywords. Likewise, a high DA site does not guarantee rankings if its content is weak.

It is also important to note that other SEO tools like Ahrefs and SEMrush have their own authority metrics. Ahrefs uses Domain Rating (DR) and SEMrush has Authority Score. These metrics are different but serve the same purpose, which is to give SEOs a way to measure site strength.

How to Improve Domain Authority and Page Authority

Improving DA and PA is a long-term process. Some of the key ways to do this include:

• Build high-quality backlinks: Focus on earning links from reputable and relevant sites.
• Publish authoritative content: Content that attracts natural links will raise both DA and PA.
• Improve internal linking: Strong internal structures help pass authority across your pages.
• Keep your site technically sound: A site with good performance, security, and usability supports higher authority.

While DA and PA are not direct ranking factors, improving them usually goes hand in hand with better overall SEO performance.

DA vs PA vs Other Metrics

Moz created DA and PA, but other SEO platforms offer their own alternatives. Ahrefs measures Domain Rating, SEMrush uses Authority Score, and Majestic provides Trust Flow and Citation Flow. These scores are all based on link data but use different formulas.

Comparing across tools can sometimes be confusing. A site might have a DA of 40 but a DR of 55. This is why it is best to pick one tool and use it consistently for benchmarking. What matters most is not the exact number but how your site compares to competitors in the same tool.

Conclusion

Domain Authority and Page Authority were introduced to fill the gap left when Google stopped showing PageRank. They have since become standard measures for SEOs when analyzing competitiveness, backlinks, and ranking potential. While they should not be seen as absolute truths, they are very useful for comparison, strategy building, and outreach.

The key takeaway is that DA and PA are indicators, not guarantees. Improving them requires the same core SEO practices that drive real rankings: publishing quality content, building strong backlinks, and maintaining a technically sound website. By understanding their history, use cases, and limitations, you can make smarter decisions about where to focus your SEO efforts.