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 Open PageRank data behind the Bulk DA PA Checker differs from Moz's index, what the link 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

Several vendors, several 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 the Bulk DA PA Checker reports a score based on Open PageRank, a free dataset from DomCop built 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 a score 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.

Open PageRank is simpler and more transparent: PageRank computed over the Common Crawl link graph, scored 0 to 10 per domain. The checker multiplies that by 10 to give its 0 to 100 score, and shows the original value and the domain's global rank alongside. Because it is measured per domain, every page on a site gets the same number. There is no page-level figure like Moz PA here, and the score will not match what Moz shows.

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 scores 92 with Open PageRank 9.2, the blog scores 38 with Open PageRank 3.8, and the new site returns No data because Open PageRank hasn't scored it yet.

The summary tiles do the comparative reading for you: 3 domains checked, 2 with data, an average score of 65, and the reference site as the strongest. The band chips group results as Low (0 to 19), Fair (20 to 39), Good (40 to 59) and Strong (60 and above), so the blog lands in Fair and the reference site in Strong. Those bands are a reading aid, not an official scale. Note that No data isn't a zero; it's a domain the dataset hasn't measured.

On a real list, tick Exclude Same Domain so several pages from one site collapse into a single row. Switch to Table view to sort by score, global rank or name, then press Download Excel or Copy CSV. Copy report link gives you a link that runs the same check again when opened, which suits a client who wants current numbers rather than a snapshot.

Authority scores and rankings: a loose correlation

Rankings are where the metric earns its skeptics. Correlation studies find authority scores relate to rankings moderately at most, 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 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

A higher score is a side effect of earning links, 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 authority scores 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.