SEO tools measure Page Authority by analyzing multiple signals that indicate the relative strength of an individual page, with backlinks being the most influential factor. The number of referring domains, link quality, relevance, and link diversity play a major role, while internal linking helps distribute authority from stronger pages to weaker ones within a website. Content quality indirectly influences Page Authority by attracting natural backlinks and sustaining engagement over time. Although Page Authority can be useful for comparing pages and estimating competitive strength, it is only moderately reliable as a predictive metric because it does not account for search intent, on-page optimization, technical SEO, or real-time ranking factors used by search engines.