Authority Metrics and How to Read Them

Every SEO tool sells you a two-digit "authority" number, and every one of them is a guess about Google, not a reading from Google. Used well, these scores track trends. Chased directly, they send you optimizing a vendor's dashboard instead of the thing it estimates.

The caveat before any number

Google's spokespeople have said plainly that Google has no single, site-wide "domain authority" score you can optimize toward. Third-party authority scores are vendor metrics. Google does not read them or use them. That is the starting point.

There is a wrinkle, and honesty requires naming it. The May 2024 Google Content Warehouse API leak exposed an internal signal named siteAuthority, which sits in tension with the public line that no such score exists. Treat this as contested. Google has not confirmed how, or whether, that signal maps to anything a vendor sells. The defensible position: Google uses site-level and page-level signals that amount to a notion of authority, publishes no score, and no third-party number equals what Google uses internally. Optimize the causes real content, real citations, real trust rather than a dashboard number.

A vendor authority score is a prediction of how you might rank, built from a vendor's own crawl. It is a thermometer, not the fever. Treat a rising score as confirmation, never as the target.

The metrics you will meet

Each tool computes its own version. The ones you will see quoted:

• Moz Domain Authority (DA): a 1 to 100 machine-learning prediction of ranking strength relative to other sites, built mainly on backlink data. Comparative, not absolute.
• Ahrefs Domain Rating (DR) and URL Rating (UR): 0 to 100 logarithmic backlink-strength scores at domain and page level. Nofollow does not pass DR.
• Semrush Authority Score: a 0 to 100 compound of link power, organic traffic, and spam signals.
• Majestic Trust Flow and Citation Flow: Trust Flow scores link quality by proximity to a trusted seed set; Citation Flow scores raw quantity.
• Moz Spam Score: the share of similar sites that were penalized or banned, a risk flag rather than a strength score.

How to read them without fooling yourself

Each vendor crawls a different slice of the web and applies an undisclosed formula. So DA, DR, and Authority Score will not match for the same site, and there is no conversion between them. Never compare a DR from one tool against a DA from another as if they measure the same thing.

The practical rule: pick one tool and use it consistently for trend-tracking. What matters is the direction of your own number over months, and how it moves against competitors measured on the same index. An absolute score in isolation tells you almost nothing. The ground truth for the links Google actually sees is the Search Console Links report, not any vendor estimate. GSC Links is ground truth →

Page-level versus site-level

One split is easy to miss and changes how you use these scores. Site-level metrics (DA, DR) describe a whole domain. Page-level metrics (Moz Page Authority, Ahrefs URL Rating, the PageRank idea) describe a single URL. They come apart in both directions: a weak site can hold one strong page, and a strong site can carry a thin, unlinked page.

This matters because Google decides ranking per page, not per site. A high domain score does not drag a poorly linked page up on its own. When you audit a specific URL's chances, read its page-level signals, not just the domain badge. The domain-wide notion of authority is only one leg of how Google judges a source; the Authoritativeness leg of E-E-A-T is the framework behind it. Authoritativeness in E-E-A-T → Next, we look past links entirely, at entity and brand authority. Entity and brand authority next →