# Domain authority: what the number does and doesn't mean
> Domain authority is a third-party model of PageRank, not a Google ranking factor. The scales are logarithmic, so equal numeric gaps represent very different link volumes. Use it to triage link prospects and judge competitive difficulty, never to judge a single link.
Source: https://rankcert.com/blog/domain-authority-explained
Published: 2026-08-29 · Updated: 2026-09-01
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Domain authority is a third-party score that estimates how strong a site's backlink profile is. Every SEO tool has its own version - Moz calls it Domain Authority, Ahrefs calls it Domain Rating, others have their own names and scales.
The first thing to understand: **Google does not use any of them.** They are not ranking factors. They are models of a ranking factor.
## What the score actually measures
Every version is a variation on the same idea, which is essentially PageRank recomputed over a third-party crawl:
1. Crawl as much of the web as you can afford.
2. Build a graph of which pages link to which.
3. Run an iterative algorithm where a page's score depends on the scores of pages linking to it.
4. Compress the result onto a friendly scale.
That is why the scores correlate with rankings without being ranking factors. They approximate the same underlying signal Google uses, from a smaller crawl.
**The scales are not linear.** Moving from 20 to 30 is common and takes a handful of links. Moving from 70 to 80 takes thousands. Most scales are logarithmic, so the gap between two high scores represents far more links than the same numeric gap lower down.
Free tool: [Domain Popularity Checker](https://rankcert.com/tools/domain-rating-checker) - Check how popular any domain is on a 0-100 score built from the Tranco top-million ranking, with its raw rank and 30-day movement.
## Why different tools disagree
Check the same domain in three tools and you will get three numbers. They differ because:
- **Different crawls.** Each index has seen a different subset of the web.
- **Different nofollow handling.** Some count nofollowed links at a discount, some ignore them.
- **Different spam filtering.** Each has its own model of which links to discount.
- **Different scales.** 0–100 logarithmic versus 0–1000 is not a rescaling you can do arithmetically.
The rank order is usually similar even when the numbers are not. That is what makes the scores useful: comparison, not measurement.
## What it is good for
**Triage.** You have 200 link prospects and time for 20. Sorting by authority is a reasonable first cut.
**Competitive context.** If everyone ranking for your target keyword sits far above you, you are not going to win it with better content alone. That tells you to pick a different keyword, which is genuinely valuable.
**Tracking your own progress.** Not the absolute number, but the direction over quarters.
Free tool: [Bulk Domain Popularity](https://rankcert.com/tools/bulk-domain-rating) - Score up to twenty-five domains at once against the Tranco top-million ranking and sort them, so you can triage a link prospect list in one pass.
## What it is bad for
**Judging a single link.** Authority is site-wide. A link from a low-traffic page buried on a high-authority site can pass almost nothing, while a link from a well-read page on a modest site in your exact niche can be excellent.
For a specific link, these matter more:
- **Topical relevance.** A link from a related site carries far more weight.
- **Outbound links on that page.** Link value divides. A page with 300 outbound links gives each one very little.
- **Is that page itself indexed and linked to?** A page nothing links to passes nothing, whatever the domain scores.
- **Does the page get traffic?** Real readers are the strongest signal that a link is real.
**Predicting rankings.** Content relevance, search intent and user signals all matter, and a well-targeted page on a weak domain routinely outranks a generic page on a strong one for a specific long-tail query.
**Judging a new site.** A domain launched three months ago scores near zero no matter how good it is. That is a statement about time, not quality.
Nobody buying your product has ever checked your domain authority. It is a diagnostic for you, not a goal. Chasing the number directly - by buying links to move it - is how sites end up with a profile that scores well and ranks badly.
## How to actually raise it
There is no direct lever. The score is a function of your backlink profile, so:
1. **Earn links from relevant sites.** See the practical version in [how to get backlinks](/blog/how-to-get-backlinks).
2. **Fix your internal linking.** Authority flows internally too. Orphan pages get none of it.
3. **Consolidate duplicates.** Three URLs serving one page split their signals three ways. Canonicals and 301s merge them back.
4. **Do not disavow reflexively.** Google ignores obvious spam links automatically. Disavowing links you did not earn and were not penalised for can only lose you value.
Expect quarters, not weeks. A link earned today may not be reflected in any tool's index for a month, or in rankings for longer.