Domain Authority: Making Sense of Third-Party Metrics
Domain Authority is a number between 1 and 100 meant to predict how well a domain will rank. It does not come from Google but from Moz – and it has imitators: Ahrefs has Domain Rating, Majestic has Trust Flow and Citation Flow, Semrush has Authority Score. This guide explains what these scores measure, where their limits lie, and how to use them sensibly.
The most important sentence first: Google has no Domain Authority metric. There is no internal value corresponding to these numbers, and none of them feeds into Google’s assessment. They are reconstructions built on the vendors’ own crawls.
1. What these scores actually are
Every one of these metrics solves the same problem: the vendor crawls as much of the web as it can, builds a link graph from it, and runs a PageRank-like computation over that graph. The result is normalised onto a convenient scale.
That means each number depends on two things that have nothing to do with Google:
- The size of the vendor’s index. Whatever they have not crawled does not exist for their calculation.
- Their own weighting. Each vendor decides how much a link counts and what qualifies as spam.
This is why the same domain can score very differently across two vendors without either being “wrong”. They are simply measuring different slices under different rules.
2. The metrics compared
| Metric | Vendor | Scale | Distinctive trait |
|---|---|---|---|
| Domain Authority (DA) | Moz | 1–100 | Trained to predict rankings; recalibrated regularly |
| Domain Rating (DR) | Ahrefs | 0–100 | Purely link-based: strength and count of referring domains |
| Trust Flow (TF) | Majestic | 0–100 | Proximity to a set of manually vetted seed sites |
| Citation Flow (CF) | Majestic | 0–100 | Raw link volume, with no quality judgement |
| Authority Score (AS) | Semrush | 0–100 | Blends link data with estimated traffic and spam signals |
The pairing of Trust Flow and Citation Flow is particularly revealing. Where CF sits far above TF, a domain has plenty of links but few from trustworthy neighbourhoods – a classic signature of bought links. A healthy profile shows both at a similar level.
3. Why the scale is logarithmic
All of these scores are logarithmic, exactly like the old toolbar PageRank. That has an uncomfortable consequence: the gaps are far wider at the top than at the bottom.
| Step | Real-world effort |
|---|---|
| from 20 to 30 | Manageable – a handful of good links often suffices |
| from 50 to 60 | Substantially harder |
| from 70 to 80 | Orders of magnitude more – barely plannable |
It also follows that a drop in your score need have nothing to do with your site. When a vendor grows its index or recalibrates, every score shifts relative to the others.
4. What Google assesses instead
Google staff have repeatedly clarified that there is no “domain authority” as an internal metric. Assessment happens primarily at the level of the individual page, not the domain.
That does not mean the domain is irrelevant. Google has confirmed it uses site-wide signals – for instance to make sense of a new URL nothing is yet known about. The distinction matters:
| Assumption | Reality |
|---|---|
| A domain has an authority score | No such single number exists |
| High authority makes any subpage rank | The individual page’s relevance and quality decide |
| The domain does not count at all | False – site-wide signals do exist |
In practice: a strong domain gives a new page a head start but does not substitute for fitting content. And a weak domain does not stop an excellent individual page from ranking.
5. Correlation is not causation
Pages with high DA rank better on average – that is true, and it is often cited as proof. The conclusion drawn from it is still wrong.
The metric is built from link data, and links correlate with rankings. So both quantities share a common cause; one does not produce the other. A DA of 60 has never lifted a page – the links behind it have.
The practical difference is considerable: optimise for the number and you buy links from high-DA pages. Optimise for the cause and you earn links from pages genuinely relevant to your topic – see backlinks.
6. What the scores are genuinely good for
Used correctly these metrics are useful – as a relative comparison, never as a target:
- Pre-sorting link prospects. With hundreds of candidates the number helps order them for manual review.
- Benchmarking competitors. If your score sits far below the field, link building is probably your bottleneck.
- Spotting anomalies. A Citation Flow far above Trust Flow is a warning sign.
- Watching the trend. The trajectory over months says more than the absolute value.
Rule of thumb: use the number to sort candidates, never to decide. The decision comes from looking at the page itself: does the topic fit? Are there real readers? Is the link inside the content or in a link list?
7. How manipulable the scores are
Because these metrics rest solely on links and nobody can check them against Google’s data, they are far easier to influence than actual rankings. Common patterns:
- Links from within the vendor’s index. Knowing which sources a tool weights heavily, you can build there deliberately.
- Expired domains. A domain with an old link profile often keeps its score long after its content has become something else entirely.
- Redirect chains. Scores can be carried onto new domains through 301 chains – for the metric, though not necessarily for Google.
So a high score alone proves nothing. A domain with DR 70 and no organic traffic at all is a loud warning sign – visible search presence is much harder to fake than a link metric.
8. Common mistakes
- Setting DA as a goal. “We want to hit 50” is not a business objective. Rankings, traffic and revenue are measurable – a third-party metric is not.
- Comparing scores across vendors. DA 40 and DR 40 are not the same thing. Only ever compare within one metric.
- Picking link prospects by the number alone. Topical fit beats any score.
- Panicking over a drop. Usually a vendor recalibration is the cause, not your site.
- Mistaking the number for Google’s view. No vendor sees Google’s link graph.
- Acting on toxicity scores. Those are equally invented – see disavow.
Pro tip: before judging a link prospect by its authority score, open it and look. Rank-O-Saur shows you indexability, title, heading structure and the number of outbound links. A page with 300 external links, thin content and a high DR is exactly the source that flatters a metric and delivers nothing.
9. Checklist for judging a link prospect
- Use the authority score for pre-sorting only, never as the sole criterion.
- Compare only scores from the same metric.
- Check Trust Flow against Citation Flow – wide gaps are a warning sign.
- Cross-check organic traffic: a high score without visibility is suspicious.
- Assess topical fit with your own site.
- Actually open the page and judge the content.
- Look at the number of outbound links on the target page.
- Consider the trend over several months rather than a snapshot.
- Measure your own goals in rankings and revenue, not in third-party metrics.
10. Frequently Asked Questions
Does Google use Domain Authority?
No. Domain Authority is a Moz metric, not a Google one. Google staff have repeatedly clarified that no equivalent internal score exists. Assessment happens primarily per page, supplemented by site-wide signals.
What counts as a good Domain Authority score?
There is no absolute target. The only meaningful comparison is against sites ranking for the same queries. Sit well below them and link building is probably your bottleneck; sit level with them and content and relevance decide.
Why did my score drop when I changed nothing?
Because the scale is relative. When the vendor grows its index or changes the calculation, every score shifts against the others. A drop without any loss of links is therefore usually a recalibration, not a problem with your site.
What is the difference between DA and DR?
Moz’s Domain Authority is trained to predict rankings and folds in several factors. Ahrefs’ Domain Rating is purely link-based, measuring the strength and count of referring domains. The two cannot be converted into each other.
What do Trust Flow and Citation Flow tell me?
Citation Flow measures raw link volume, Trust Flow measures proximity to manually vetted trustworthy sites. The ratio is what matters: Citation Flow far above Trust Flow suggests many links from low-trust neighbourhoods.
Should I only buy links from high-authority sites?
Buying links violates Google’s guidelines regardless of the source’s authority score. Beyond that, a high score is easy to manipulate: a domain with high DR and no organic traffic has typically been built for exactly that purpose.
How do I increase my Domain Authority?
By increasing what the metric measures: links from strong, topically relevant domains. The number is a by-product, not a goal – optimising for it directly leads quickly to bought links, which Google devalues.
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