Page Authority is a third-party metric (specifically Moz's own) that estimates how likely a single, specific page is to rank well in search results, based primarily on that page's own backlink profile, scored on a 1-100 scale.
Page Authority is the page-level counterpart to Domain Authority, which scores an entire domain rather than one specific page — both are Moz's own proprietary metrics, not an official Google score, and other providers calculate their own similarly-purposed but differently-methodology'd equivalents (Ahrefs' URL Rating, for example). Because it's calculated primarily from a page's own backlink profile, a newly published page on an otherwise well-established, high-authority site will typically start with a low Page Authority score of its own, since the individual page hasn't yet accumulated links pointing directly at it — the domain's overall strength doesn't automatically transfer a high score to every new page on it. Like Domain Authority, scores from different providers use different methodologies and aren't directly comparable to each other, and the metric itself isn't something Google has confirmed using or calculating.
Page Authority is most useful as a relative, within-provider comparison tool — judging which of your own pages has accumulated the strongest link profile, or comparing your page against a specific competing page for the same term — rather than as an absolute, cross-tool, or Google-confirmed indicator of ranking strength.
Illumae's backlink checker shows domain authority and spam-risk banding for individual backlinks pointing at your site, rather than a single page-level authority score in the way Page Authority specifically measures.
Domain Authority scores an entire domain's overall strength; Page Authority scores one specific individual page, based primarily on that page's own backlink profile rather than the domain's as a whole. A high-authority domain can still have individual pages with low Page Authority if those specific pages haven't accumulated their own backlinks.
Because Page Authority is calculated largely from the specific page's own backlink profile, not inherited automatically from the domain's overall strength — a brand-new page simply hasn't had time to accumulate links pointing directly at it yet, regardless of how strong the rest of the domain is.
No — it's Moz's own proprietary third-party metric, not something Google calculates, publishes, or has confirmed using directly as a ranking signal.
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