Page authority(PA)
Page authority is a URL-level score estimating how likely a single URL is to rank in search results. Moz coined the metric as a 1-100 logarithmic scale. Google uses its own internal signals, not Moz's; PA is a correlated proxy, not ground truth. High PA does not guarantee ranking.
Long definition
Page authority and its sibling Domain Authority (DA) are Moz's attempts to model Google's ranking strength from a combination of signals Moz can observe from outside: the link graph crawled by Moz's Linkscape/Mozscape, anchor text distributions, and dozens of correlated features. Similar proxies: ahrefs' URL Rating (UR), Majestic's Trust Flow, Semrush's Authority Score. Each tool's model is different and non-interoperable.
Google does not use Moz's PA internally. Google uses its own signals — PageRank (still real, just no longer public), topical authority, content quality signals, user engagement — to rank URLs. What PA tells you is roughly "how strong does this URL look to an external observer with good link data." That correlates with ranking strength but isn't identical to it.
PA is most useful for:
- Competitive analysis — comparing your URL against competitors on the same SERP. Relative comparisons are more meaningful than absolute values.
- Link prospecting — screening potential link-building targets. A site with consistent high PA on its category pages is a better link donor than one with high homepage PA and nothing else.
- Redirect prioritization — during migrations, the high-PA URLs are the ones whose redirects you absolutely cannot afford to break.
Common misconceptions
- "PA is a Google metric." It isn't. Moz computes it from their crawl of the web. Google has never endorsed PA or any third-party metric.
- "PA 50 beats PA 45." The scale is logarithmic. The gap between PA 60 and PA 70 is much larger than the gap between PA 20 and PA 30. Treat differences of less than 3-5 points as noise.
- "High PA means it will rank." PA measures how a URL looks to an outside observer. Relevance to the query and user intent signals — neither of which PA captures well — decide whether that strength converts to a ranking.
- "DA drives rankings, not PA." URL-level signals matter more for specific-query rankings; site-level signals matter more for a site's baseline capacity. Both are proxies. Neither is the thing Google measures.
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