What Is Page Authority and How Does It Work?
Page Authority (PA) is a metric developed by Moz that predicts how likely a specific web page is to rank in search engine results pages (SERPs). Scored on a logarithmic scale from 1 to 100, Page Authority incorporates data from Moz's Link Explorer index, analyzing dozens of factors related to a page's backlink profile, link equity, and overall link-based trust signals to produce a single, actionable score.
The PA algorithm is built on a machine learning model that was trained by correlating known ranking factors with actual search engine results across millions of queries. This means Page Authority does not simply count links; it weighs the quality, relevance, diversity, and trustworthiness of every link pointing to a page, along with several other proprietary signals, to produce a score that closely correlates with real-world ranking performance.
Understanding how Page Authority differs from related metrics is essential for using it effectively:
- Page Authority vs. Domain Authority: Domain Authority (DA) evaluates the overall ranking strength of an entire domain, encompassing all pages on the site. Page Authority evaluates a single URL in isolation. A website can have a high DA but still contain individual pages with low PA if those specific pages lack strong backlinks. Conversely, a page on a lower-DA domain can achieve a high PA if it has earned exceptional links on its own merit.
- Page Authority vs. MozRank: MozRank is a pure link popularity metric that measures the quantity and quality of incoming links. Page Authority is a broader predictive score that includes MozRank as one of its many input signals but also factors in link diversity, anchor text distribution, social signals, spam analysis, and other variables. PA provides a more comprehensive ranking prediction than MozRank alone.
- Logarithmic scaling: Because the scale is logarithmic, improving your PA from 20 to 30 is significantly easier than improving from 70 to 80. Each incremental point at higher levels requires substantially more link equity and authority. This scaling reflects the competitive reality of search rankings, where the difference between positions one and two on Google is often determined by marginal authority advantages.
PA scores are relative and comparative, meaning they are most valuable when used to compare one page against another rather than evaluated in absolute terms. A PA of 45 is not inherently good or bad; its significance depends entirely on the PA scores of the pages you are competing against for specific keywords. If your target SERP is populated by pages with PA scores in the 30s, a PA of 45 gives you a strong competitive advantage. If competitors have PA scores in the 60s, significant improvement is needed.
Moz recalculates Page Authority regularly as their link index is updated and their machine learning model is refined. This means PA scores can fluctuate over time, not only because of changes to your own link profile but also because of improvements to the scoring algorithm itself. Always focus on the relative trend of your PA over time rather than fixating on a specific number.