DA, DR and Trust Flow are not Google metrics: what each one measures, when it helps and how to measure links instead

Domain Authority, Domain Rating and Trust Flow are numbers from 0 or 1 to 100 that SEO tools put next to every website. Agencies sell links by them, domain brokers price names by them, and plenty of monthly reports treat them as the headline result. None of them is a number Google calculates or uses. Each one is a vendor's model of a link graph the vendor crawled itself.

That doesn't make them useless. It makes them tools for specific jobs. This article sets out how each vendor says its metric is computed, what Google has said in public, where the scores help, where they mislead, and what to measure instead.

Every claim below carries one of four labels: official guidance (a platform documenting its own product, including a vendor documenting its own metric), research finding, our observation, or hypothesis. The vendor and Google pages were checked on 2026-10-06. Methodologies change, so re-check them before you rely on this after early 2027. Register ids (DA-01, RQ1-02 and so on) point to our evidence register.

What each metric is, in the vendor's own words

Metric	Vendor	What the vendor says it models	Scale and behavior
Domain Authority (DA)	Moz	A machine-learning model, built mainly on backlink data from Moz's own index, that predicts how likely a domain is to rank relative to other domains	1 to 100. Relative: when the strongest sites gain links, everyone else's score can fall
Domain Rating (DR)	Ahrefs	The strength of a domain's backlink profile, from followed links only, with each linking domain's rating split across all the domains it links to	0 to 100, logarithmic, rescaled across the whole index
Citation Flow (CF)	Majestic	How much link "power" points at a URL or site, looking through the wider link network, regardless of link quality	0 to 100
Trust Flow (TF)	Majestic	How closely a URL or site is linked to a set of seed sites Majestic reviewed by hand and considers trustworthy	0 to 100

Moz DA (official guidance, Moz Learning Center, last updated 2025-03-18, DA-01). Moz describes DA as a score that predicts how likely a site is to rank against competitors. It is calculated by a machine-learning model that leans mostly on backlink data: linking root domains, the quality of those links, and other signals that correlate with rankings. Moz states plainly that DA is not a Google ranking factor and has no effect on search results. It calls DA a comparative metric, says there is no universal "good" score, and explains that growth gets harder near the top because established sites hold the high slots.

Ahrefs DR (official guidance, Ahrefs Help Center, page dated 2026-09-03; Ahrefs blog on DR, DA-02). Ahrefs counts domains with at least one followed link to the target. Only the first link from each domain counts. A linking site's rating is divided equally across every domain it links to, so a small site linking to three domains can move DR more than a huge site linking to a million. The result is rescaled to 0 to 100 on a logarithmic scale. Ahrefs says DR ignores search traffic, and that large numbers of low-quality links can raise DR rather than lower it. It also says DR can drop without you losing a link, because the index is rescaled when the top sites grow.

Majestic CF and TF (official guidance, Majestic glossary and Flow Metric scores, DA-03, DA-04). Citation Flow reflects how much link equity points at a URL, subdomain or domain, and Majestic says it does not care whether those links are good or bad. Trust Flow starts from seed sites that Majestic collated by manual review and models how trust passes outward from them. Majestic says the two scores together are used for toxic link analysis and penalty clean-up, and that it is rare for a site's TF to exceed its CF. Topical Trust Flow splits the seed set into topic pools so a score can say which subject a site's links come from.

What the three vendors agree on is worth noticing. Each one says its score is relative: compare like with like, not against a fixed target. Each one says its score moves when the model or index changes, not only when your links change. Majestic suggests looking at long-term trends because its algorithms are revised, and says outright that Flow Metric scores do not directly influence search engines (DA-04). Ahrefs says there is no evidence search engines use DR, DA or similar scores as a ranking factor (official guidance, RQ1-03).

What Google has said

Google has never published a "domain authority" score, and its staff have said several times that it doesn't use one.

• Its documentation names no third-party score. Google's guide to its ranking systems lists link analysis and PageRank among many systems. It says those systems work mainly at page level, with some site-wide signals (official guidance, ranking systems guide, RQ1-01).
• Google's Search Advocate has said it doesn't use DA. In February 2020 John Mueller said Google does not use Domain Authority in its algorithms, while also confirming Google still uses PageRank internally (official guidance, staff statement, RQ1-02). In 2016 he said Google has nothing like a website authority score, while noting that some signals look at a site overall (DA-05). In January 2022 he said Google doesn't count links at domain level (DA-06). These are dated staff statements, not documentation, and Google can change.
• No outside tool can see inside Google. Google's generative AI search guide says no third-party tool has access to its internal ranking or AI systems (official guidance, AI optimization guide, M1-13).

Read these carefully, because they don't say links are irrelevant. Links still matter to Google, through PageRank and link analysis (RQ1-01). Google also admits some site-level signals exist (RQ1-01, DA-05). Ahrefs points out that a strong site can pass link equity to a new page through internal links, so a domain's link profile can matter indirectly (RQ1-03). The accurate statement is narrow: the vendor score is not an input. The links it summarizes may well be. Some practitioners argue that Google has its own site-level quality signals and that DA roughly tracks them. Google's documents don't say what those signals are, so whether any vendor score approximates them is a hypothesis.

Where the scores are useful

A vendor score is a fast, consistent summary of a link graph you can't crawl yourself. Used that way, it earns its place (our method, hypothesis unless noted).

1. Comparing link profiles in one tool. Put your site and the sites ranking for your target queries in the same tool, on the same day. A large gap in referring domains or DR tells you links are probably part of what you're up against. This is the use all three vendors recommend (DA-01, DA-02, DA-04).
2. Triage when there are too many domains to read. Sorting hundreds of referring domains or outreach prospects by score lets you read the top and bottom of the list first. It doesn't replace reading them.
3. Spotting an odd profile. Majestic designed TF and CF to be read together, and says TF rarely exceeds CF (DA-04). A domain with high Citation Flow and very low Trust Flow has a lot of links and little connection to trusted seed sites. That pattern is worth a closer look in a domain purchase or a link audit.
4. Tracking your own link acquisition over long periods. A slow climb in referring domains over a year says more than any single month's DR. Majestic recommends long-term trends for exactly this reason (DA-04).

How we use TF and CF when vetting a domain. In our domain checklist we treat a Trust Flow to Citation Flow ratio of about 0.3 or higher as unremarkable, 0.15 to 0.3 as a reason to look harder, and below 0.15 as a strong reason to walk away unless the backlinks check out by hand. Those cut-offs are our screening heuristic. Majestic publishes no ratio threshold (DA-04), Google publishes nothing about TF or CF, and we have not validated the cut-offs against outcomes. Use them to decide which domains to inspect, then decide on what the inspection finds: the referring sites themselves, archive snapshots and anchor text.

Where they mislead

They aren't a Google input, so raising them isn't the goal. Majestic says there is little to gain from raising Flow Metric scores for their own sake, and that a higher score should follow good work rather than cause it (official guidance, DA-04). Moz and Ahrefs say their scores are not ranking factors (DA-01, RQ1-03).

They make poor KPIs. A KPI should move when your work succeeds and stay put when it doesn't. Vendor scores fail both tests:

• They move when the vendor recrawls, reweights or rescales its index, even if nothing changed on your site (DA-01, DA-02, DA-04).
• DR rises with low-quality links, by Ahrefs' own account (DA-02). A target of "DR 50 by Q4" rewards exactly the links you don't want.
• They measure domains. Google ranks pages for queries (RQ1-01, DA-06). A rising domain score says nothing about whether your pricing page ranks for the query that brings buyers.
• They don't touch revenue. No vendor score includes your signups, qualified pipeline or retention.

Different tools give different numbers. Each vendor crawls its own index and builds its own model, so (to take an invented example) DA 40, DR 55 and TF 20 could all describe the same site on the same day. Don't mix tools in one comparison and don't compare across tools over time (our observation, from reading the vendor methods above).

They're easy to game, and selling links by them invites risk. A "high DA" link package is a price list for links. Google's spam policies define link spam as links made mainly to manipulate rankings, and name buying or selling links for ranking purposes as a violation. Paid links are fine when marked rel="sponsored" or rel="nofollow" (official guidance, spam policies, link spam, page dated 2026-08-28, DA-07). If a vendor score is the main thing a link seller advertises, treat it as a warning, not a selling point.

Traffic estimates are models too. The organic traffic figures these tools show are estimates built from rankings and assumed click-through rates, not measured visits. Compare a tool's estimate for your own site against your Search Console clicks before you trust its estimate for anyone else's (our method, hypothesis; we haven't published a comparison).

A note on old claims. You'll still read that Google "unrolls" link networks after the fact and punishes every site connected to them. What Google has documented is narrower. Its spam policies say sites that violate them may rank lower or not appear at all (DA-07). Its December 2022 link spam update post says SpamBrain, its AI spam-prevention system, can detect both sites buying links and sites used to pass outgoing links, and that unnatural links are neutralized so the credit they passed is lost (official guidance, Search Central blog, 2022-12-14, DA-09). Neither page describes when networks are detected or says every connected site is punished. So a known link network in a domain's history is a good reason to walk away: the links may already count for nothing, and a manual action is possible. "Google will unroll it retroactively" is a practitioner claim (hypothesis), not a documented timeline.

A safer measurement plan

Measure the links themselves and what they do for the pages you care about. Keep vendor scores as context columns.

1. Track links you can verify. Search Console's Links report shows top linking sites, top linked pages, anchor text and internal links from Google's own data (official guidance, Links report, DA-08). Know its limits: it's a sample, tables stop at 1,000 rows, exports stop at 100,000 rows, it doesn't flag nofollow, and it doesn't tell you which links Google values or ignores (DA-08). Use one third-party index alongside it for coverage, and keep using the same one.

2. Keep a link log. One row per link you earn or build: date found, linking page, target page, rel attribute, whether the linking page is indexed, and whether it sends referral sessions. Referral traffic from a link is a real, measured outcome. A score change isn't (our method).

3. Measure the target pages, not the domain. In Search Console's Performance report, filter by page and watch clicks, impressions and average position for the query group each page targets (official guidance, M1-15). Remember that rare queries drop out once you apply a query filter, so filtered totals undercount (M1-15).

4. Use a control set. Pick similar pages that received no new links in the same window. Compare equal time windows and note Google updates, launches and campaigns. A ranking gain after a link, with no control, doesn't show the link caused it (our method; see the BOFU pages article for the same design).

5. Tie it to the business. Report key events and pipeline by organic landing page, then qualified opportunities and retention from your CRM. If a link campaign produces no change in qualified demand for the pages it targeted, the campaign didn't work, whatever the scores did.

6. If you must report a vendor score, report it honestly. One tool, one date each month, the competitor set alongside it, and a footnote saying it's a vendor estimate, not a Google metric. Never set it as a target.

Checklist

• Every report that shows DA, DR or TF says which vendor and which date, and says it isn't a Google metric.
• Comparisons use one tool, the same day, and real competitors for the target queries.
• No targets or bonuses are tied to a vendor score.
• Domain and link vetting uses scores to choose what to inspect, then decides on the inspection.
• Any TF:CF cut-off is labeled as a screening heuristic.
• Paid placements are marked sponsored or nofollow. Nobody buys links by score.
• A link log records each link's rel attribute, indexing and referral sessions.
• Target pages are measured in Search Console against a control set.
• Results are reported as qualified demand, not as score movement.

If you'd rather have someone set this up on your site, RankPropel's audit and baseline sprint covers priority pages, lead-source measurement and the baseline a link program needs. The method works the same if you do it yourself.

Sources

Vendor documentation: Moz, Domain Authority (last updated 2025-03-18); Ahrefs Help Center, What is Domain Rating and Do search engines use DA or DR as a ranking factor? (both dated 2026-09-03); Ahrefs blog, Domain Rating; Majestic, glossary and Flow Metric scores. Google Search Central: ranking systems guide, spam policies (page dated 2026-08-28), December 2022 link spam update, optimizing for generative AI search. Search Console Help: Links report, Performance report. Google staff statements (John Mueller) as reported by Search Engine Roundtable: February 2020, October 2016, January 2022. All retrieved 2026-10-06.