Domain authority is a score that estimates how strong a website's backlink profile is, usually on a 0–100 scale. The best-known version is Moz's Domain Authority (DA); Ahrefs has Domain Rating (DR), Semrush has Authority Score, and Open PageRank offers a free alternative. The single most important fact about all of them: none is a Google metric. They're third-party estimates of link strength, not numbers Google uses to rank pages.
That doesn't make them useless. Used carefully, authority scores are a fast way to compare sites and filter link prospects. Used carelessly, they lead people to chase inflated numbers, pay premiums for manufactured scores and ignore what actually matters — relevance and real traffic.
This guide explains what each metric measures, DA vs DR side by side, why the scores disagree, how to use them when vetting links, how to grow your own authority, and how HrefClub Authority works.
What is domain authority?
Definition
Domain authority is a general term for third-party scores that estimate a website's overall strength based mainly on the quantity and quality of sites linking to it. “Domain Authority” (capitalized, DA) is specifically Moz's metric.
Every major SEO tool has its own version, and most also have a page-level equivalent (Moz's Page Authority, Ahrefs' URL Rating) that scores an individual URL rather than the whole domain. All of them try to approximate the same intuition behind Google's original PageRank idea: a link from a site that is itself well linked counts for more than a link from a site nobody links to.
Is domain authority a Google ranking factor?
No. Google doesn't use Moz DA, Ahrefs DR, Semrush Authority Score or Open PageRank, and Google representatives have said so publicly many times. These companies don't have access to Google's data; they run their own crawlers, build their own link indexes and apply their own models.
What's true is more nuanced:
- Links still matter to Google. Google uses links — including PageRank-derived signals — as one of many ranking factors. It stopped showing public PageRank scores years ago (the toolbar score was retired in 2016), which is partly why third-party metrics filled the gap.
- Authority scores often correlate with rankings. Sites with strong link profiles tend to rank well, so a high score and good rankings often go together. Correlation isn't causation: raising the score without earning genuinely valuable links won't move Google.
- Google works mostly at the page level. It ranks pages, not domains. A strong domain helps, but a weak page on a strong site can still lose to a great page on a smaller one.
The practical takeaway
How DA, DR, Authority Score and Open PageRank work
Each vendor publishes a high-level description of its metric but not the exact formula. Here's what they broadly measure, based on their own descriptions.
Moz Domain Authority (DA)
Scored 1–100. Moz describes DA as a prediction of how likely a site is to rank in search results compared with other sites, produced by a machine-learning model trained on its link data. Linking root domains (the number of unique sites linking to you) and the quality of those links are central inputs. The scale is logarithmic, so each step up gets harder.
Ahrefs Domain Rating (DR)
Scored 0–100. Ahrefs describes DR as a measure of the strength of a site's backlink profile relative to others in its database. Broadly, it looks at how many unique domains link to a site with followed links, how strong those domains are themselves, and how many other sites they link out to. DR is purely link-based — it doesn't factor in traffic — and it's also logarithmic.
Semrush Authority Score (AS)
Scored 0–100. Semrush describes Authority Score as a compound metric combining link power (the quality and quantity of backlinks), estimated organic traffic, and signals about how natural the link profile looks. Including traffic and spam signals makes it harder to inflate with links alone.
Open PageRank
A free metric that applies a PageRank-style calculation to openly available web-crawl link data. It reports a score from 0 to 10 with decimals and can be queried in bulk through a free API, which makes it practical for scoring large numbers of domains consistently. It's the basis for HrefClub Authority, covered below.
Other tools exist too — Majestic's Trust Flow and Citation Flow, for example, separate the trustworthiness of linking sites from the raw volume of links. The same principle applies to all of them: useful as a relative signal within one tool, not comparable across tools.
DA vs DR side by side
| Moz DA | Ahrefs DR | Semrush AS | Open PageRank | |
|---|---|---|---|---|
| Scale | 1–100 | 0–100 | 0–100 | 0–10 (decimal) |
| Main inputs | Link data via a machine-learning model | Followed referring domains and their strength | Links, estimated organic traffic, naturalness signals | PageRank-style calculation on open crawl data |
| Includes traffic? | No | No | Yes | No |
| Page-level version | Page Authority (PA) | URL Rating (UR) | Page-level score available | — |
| Cost | Paid tool (limited free checks) | Paid tool (limited free checks) | Paid tool (limited free checks) | Free API |
| Used by Google? | No | No | No | No |
So which is better, DA or DR? Neither is “right,” because there's no Google number to check them against. DR is easy to reason about because it's purely link-based. Authority Score's traffic component makes it a bit harder to game. The best choice is usually whichever tool you already use — consistently, for every comparison.
Why authority scores disagree
It's common to see a site with DA 25, DR 45 and an Authority Score of 18. That's not an error — it's expected. Here's why:
- Different crawlers, different indexes. Each tool discovers a different subset of the web's links. A link one tool has found, another may never have seen.
- Different models. One counts only followed links, one blends in traffic, one uses machine learning trained on rankings. Same inputs, different weights, different outputs.
- Different spam filtering. Tools vary in how aggressively they discount links from link farms, PBNs and spammy sites.
- Relative scaling. Scores are calculated relative to everything else in each tool's index, so when the index grows or the model is updated, scores across the web can shift even if nothing changed on your site.
- Update timing. Tools refresh on different schedules, so a recent batch of links may show up in one before another.
- Manipulation. Purely link-based scores can be inflated by buying links from sites with high scores. That's why a big gap between a link-only score and a traffic-aware one is worth a closer look.
Watch for authority without traffic
How to use authority metrics sensibly when vetting links
Authority scores are a good first filter and a poor final decision. When you're judging whether a link opportunity is worth having, put them in their place:
- 1
Start with relevance
Is the site about your topic or a closely related one? Would your audience read it? A relevant site with modest authority usually beats an irrelevant one with a high score. - 2
Check real organic traffic
Look at estimated traffic and its trend. Traffic means Google trusts the site enough to send it visitors — the closest thing you'll get to Google's opinion. - 3
Look at the specific page
Is the page indexed? Does it have links of its own or rank for anything? Where would your link sit, and how many other outbound links share the page? - 4
Use authority as a sanity check
Compare it within one tool against the other prospects on your list. Treat a high score with no traffic, or a sudden jump, as a red flag rather than a selling point. - 5
Inspect outbound links
A site that links out to commercial sites on unrelated topics in nearly every post is likely selling links, whatever its score.
Good uses of authority scores
- Shortlisting prospects quickly
- Comparing your site with competitors in one tool
- Spotting mismatches between authority and traffic
- Tracking your own link growth over time
Bad uses of authority scores
- Paying per point of DA or DR
- Rejecting relevant sites just because the score is low
- Comparing a DA from one tool with a DR from another
- Treating the score as a ranking target
Authority also drives price on the open market, which is why it features heavily in our breakdown of how much backlinks cost.
How to increase domain authority
Because every authority metric is built on links, there's really only one way to raise it durably: earn more links from sites that are themselves well linked and relevant. The ways to do that are the same ones that help in Google:
- Publish linkable assets. Original data, tools, in-depth guides and templates attract citations. Thin content doesn't.
- Do outreach for pages that deserve links. See our guide on how to get backlinks for the tactics that work, including broken link building.
- Earn coverage. Digital PR and expert commentary can bring links from news and industry sites, which tend to be strong.
- Reclaim lost and unlinked mentions. Ask sites that mention your brand without linking, or whose links to you broke, to fix them.
- Diversify referring domains. Many links from one site count for far less than one link each from many sites.
- Be patient. Scores are roughly logarithmic, so early gains come faster and later ones slow down. For a new site, see our guide to link building for new websites.
Shortcuts that inflate the number but not your rankings
Monthly authority health check
0/6How HrefClub Authority works
HrefClub needs one consistent way to score every member site so that link tiers mean the same thing for everyone. That score is HrefClub Authority:
- Based on Open PageRank data. We take a site's Open PageRank score (0–10) and express it on a 0–100 scale, similar in spirit to DR or DA.
- Refreshed monthly. Scores are re-fetched about every 30 days, so tiers keep up as sites gain or lose links.
- Decides which tiers a site can serve. When you request a link, you choose a minimum authority tier, and only member sites at or above it are matched to your request.
| Tier (minimum HrefClub Authority) | Cost per link | Who can host it |
|---|---|---|
| Any authority (0–19) | 1 credit | Any eligible member site |
| 20+ | 2 credits | Sites scoring 20 or more |
| 40+ | 4 credits | Sites scoring 40 or more |
| 60+ | 8 credits | Sites scoring 60 or more; requesting this tier requires Gold trust (90+) |
Authority is only half the picture. Because a score alone can be inflated, every site also gets a separate Site Quality score based on content depth, freshness, outgoing links, domain age, authority and traffic. Link farms and sites that sell links can't host, regardless of their authority, and links are still matched by niche and placed inside real page content.
As with every authority metric, HrefClub Authority isn't a Google score and doesn't guarantee rankings. It's a consistent, transparent way to price and match links — combined with the relevance and quality checks that matter more.