SEO Tools·4 min read

What Domain Authority Measures, and What It Leaves Out

Every SEO report has an authority score in it, and almost every client assumes Google made that number. It didn't. Understanding what domain authority measures, and just as importantly what it doesn't, keeps those scores useful instead of misleading. This article covers where DA and PA come from, how the DA PA Checker's Open PageRank data differs from Moz's index, what the correlation with rankings actually looks like, and how to move the number without wasting a quarter chasing it.

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DA and PA: the authority metrics Google never built

Five vendors, five scales, zero Google.

Domain Authority and Page Authority are Moz products, launched to fill the hole left when Google stopped publishing PageRank scores. Ahrefs has Domain Rating, Semrush has Authority Score, and this site's DA PA Checker reports an authority figure from Open PageRank, a free dataset built by DomCop on Common Crawl's link graph. Different companies, different scales, none of them used by Google.

That's not a dismissal. Third-party authority scores compress a domain's entire link profile into one comparable number, and comparison is genuinely useful. Sorting 200 outreach prospects by hand would take a day; sorting them by an authority column takes a click. The trouble starts only when the number gets presented as a Google metric.

What domain authority measures under the hood

Moz's DA is a machine learning model. It examines a domain's link profile in Moz's crawl, linking root domains, total links, the quality of the linkers, and predicts how well the domain should rank relative to others. It's scored 0 to 100 on a logarithmic scale, so climbing from 20 to 30 takes far less than 70 to 80. PA applies the same idea to a single URL.

The Open PageRank score behind this tool is simpler and more transparent: PageRank computed over the Common Crawl link graph, normalized to 0 to 100, with the classic 0 to 10 value shown alongside. Different data, same underlying question: how much link equity points at this domain?

A worked bulk authority check on a prospect list

Three domains, one paste.

Paste three domains into the checker: a major reference site, a mid-tier niche blog, and a site registered last spring. Press Check DA PA. Output: the reference site shows authority 91 with PageRank 8, the blog shows 38 with PageRank 4, and the new site returns No data because Open PageRank hasn't scored it yet.

The summary tiles do the comparative reading for you: three domains checked, two with data, average 65, strongest 91. Export to Excel and a raw prospect list becomes a sortable authority column in under a minute. Note that No data isn't a zero; it's a domain the crawl hasn't measured.

DA vs actual rankings: a loose correlation, honestly stated

The da vs actual rankings question is where the metric earns its skeptics. Correlation studies find authority scores relate to rankings moderately at best, and the correlation runs mostly through the one thing both share: links. On any specific query, a focused page on a 25 authority domain routinely outranks a thin page on a 60.

Google's spokespeople have said flatly that no site-wide authority score of this kind exists inside the algorithm. Use the score for what it can do, ranking a list of domains against each other, and never for what it can't: predicting the outcome of a single keyword battle.

Authority score mistakes that mislead reports

Five ways an authority number goes wrong in a slide deck:

Presenting DA or any authority score as a Google metric, which a client will eventually discover it isn't.
Comparing numbers across tools, when Moz, Ahrefs, and Open PageRank use different data and different scales.
Chasing the score with directory and comment links that inflate counts without adding ranking power.
Panicking over small monthly drops that reflect recalibration of the whole scale, not lost ground.
Judging a specific page by its domain's score, when that page might have no links at all.

Improving authority metrics without gaming them

Improving authority metrics is a side effect of link earning, not a strategy of its own. The work that moves the score, digital PR, genuinely citable resources, fixing link-worthy pages that load too slowly, is the same work that moves rankings, so aim at rankings and let the score follow.

Two accelerants are underrated. Internal linking concentrates the authority you already have onto the pages that need it most. And reclaiming lost links, unlinked brand mentions, moved pages returning 404 to old backlinks, is the cheapest authority available anywhere. Neither shows up in a link building invoice, which is probably why both stay neglected.

Reading the DA PA gauges next to the site's other checkers

Authority is one axis of evaluating a domain. The Domain Age Checker adds the time axis, which matters when an impressive score sits on a suspiciously young registration. The Link Extractor shows what a specific page does with its authority, anchor by anchor. And the Broken Link Checker hints at maintenance quality, which no link graph captures. Two or three of these views together read a domain far better than any single score.