A client asks why their Domain Authority is 3. A link seller promises to push it past 50 by next month. Neither conversation goes well unless you know what the number actually measures, so this guide explains how Moz builds Domain Authority, how to check it for free, and what happened when four SEO tools scored the same small website on the same day.
Why Domain Authority Confuses So Many Site Owners
People who search for “domain authority moz” usually want two things: a quick way to check a score, and a straight answer about whether it matters. Moz handles the first with a free checker that allows 3 reports a day without a login (Moz Domain Authority Checker). The second answer takes longer, because Domain Authority is a prediction built from links, not a grade that Google hands out.
The confusion grows the moment you open a second tool. Ahrefs, Semrush and SE Ranking each publish their own authority score, and some free tools show Moz’s number inside their own dashboards. So is a site with a DA of 3 weak? Compared with what?
We ran into this ourselves. On October 21, 2026, we looked up a small marketing website our own team runs in Mangools, Ubersuggest, Semrush and SE Ranking, as one step of the same task list in each tool. The authority scores came back as 3, 3, 7 and 15. None of them was wrong. They were answering different questions.
This guide sticks to two kinds of evidence: what Moz’s own documentation says about Domain Authority, and what our test log recorded on that day. We did not run Moz Pro itself in that test, so everything about Moz’s tools below comes from Moz’s pages, not from our screens.
Key Takeaways
Authority scores mostly agree on which sites are strong: a 2023 peer-reviewed study of 3,151 domains found Spearman correlations above 0.9 between Moz’s Domain Authority, Semrush’s Authority Score and Ahrefs’ Domain Rating (Reyes-Lillo, Morales-Vargas and Rovira, Profesional de la información). The absolute numbers still differ, especially on small sites. Domain Authority runs from 1 to 100, is not a Google ranking factor, and only means something next to your competitors’ scores.
Moz Domain Authority in Short: What the Score Means and Where to Check It
Domain Authority (DA) is “a search engine ranking score developed by Moz” that predicts how likely a website is to rank compared to competitors, on a scale from 1 to 100 (Moz Learning Center). Higher scores mean a greater predicted ability to rank. That is the whole definition. Everything else is detail about how Moz gets there.
Three facts from that same Moz page matter more than the number itself:
- It’s relative. Moz calls DA “a comparative metric” and says it is most useful for benchmarking within your industry.
- It’s built on links. The score comes from Moz’s Link Explorer index and “uses dozens of factors,” but the quality and quantity of backlinks weigh the most.
- It isn’t Google’s. In Moz’s words: “Domain Authority is not a Google ranking factor and has no effect on the SERPs.”
Where can you check it? Moz lists four places: the free Domain Authority checker, Link Explorer with a free Moz Community account, the MozBar browser extension, and Domain Overview inside Moz Pro. For one site, the free checker is the quickest. For tracking a site over months, Link Explorer and Moz Pro keep the history.
Why does Moz own the term at all? Because Moz coined it. Its checker page calls DA “the original Domain Authority metric from the team who coined the term,” and several other tools that show a “DA” are in fact reading Moz’s data, as our four-tool test shows further down. If you’re new to the company behind the metric, our guide to what Moz is and what Moz Pro, Moz Local and the free tools do covers the wider product line.
How to Check Domain Authority With Moz’s Free Tool, Step by Step
Moz’s free Domain Authority checker allows free users “up to 3 reports per day,” according to its Help Hub guide (Moz Help Hub: Domain Authority Checker). You don’t need an account for those three reports. Here is the process Moz describes:
- Open Moz’s free Domain Authority checker (the page is called Domain Analysis).
- Enter the domain you want to research.
- Click the Check DA button.
- Read the top-level metrics: Domain Authority, Linking Root Domains, Ranking Keywords and Spam Score.
Below those numbers, the same guide lists three link modules in the report:
- Top Pages by Links: the site’s most important pages, ranked by Page Authority.
- Top Linking Domains: the sites that link to the domain, ranked by their own Domain Authority.
- Discovered and Lost Linking Domains: the linking domains Moz found or lost in the last 60 days.
The product page adds keyword data to the same report: top-ranking keywords, keywords by estimated clicks, top featured snippets and top search competitors (Moz Domain Authority Checker). That makes the free report more than a score. It’s a quick snapshot of who a site competes with.
When three reports a day isn’t enough
What if you need more than three? Moz’s Link Explorer gives “10 free queries per month” once you create a free Moz Community account and verify your email (Moz Link Explorer). It shows Domain Authority, Page Authority, Spam Score and link counts for any site, plus graphs of DA over time. Note the different budget: the checker resets daily, while Link Explorer’s free queries are counted per month.
Past that, the next step is paid. The plan limits and the trial terms are laid out in our breakdown of Moz Pro plans, costs and the free trial.
Read the report before you quote the number
One habit saves a lot of confusion. Before you put a DA into a report, scroll down to the linking domains. A DA of 12 built on a handful of real, related sites tells a different story from a DA of 12 built on directory listings. The score can’t tell you which one you’re looking at. The list can. Those lists also differ from tool to tool, as our test of four backlink checkers on the same website shows.
How Moz Calculates Domain Authority
Moz calculates Domain Authority “using a machine learning algorithm that evaluates multiple factors, primarily focusing on backlink data” (Moz Learning Center). The index behind it holds 45.5 trillion links, 8.7 trillion URLs and 1 billion domains, according to Moz’s Domain Authority checker page.
What goes into the model
Moz names the main inputs: “the number of linking root domains, the quality of those links, and other signals that correlate with rankings across thousands of search results.” A linking root domain is a unique website that links to you. Ten links from one blog still count as one linking root domain.
The model is trained against real search results. Put simply, Moz looks at which sites actually rank, finds the link patterns that best predict that, and then scores every domain on those patterns. That’s why Moz frames DA as a prediction of “how likely a website is to rank” rather than a measurement of anything Google does.
Does that make DA useless? Not at all. It just means DA answers one narrow question well: how does this site’s link profile compare with other sites’?
How Moz collects the links
The links come from Moz’s own crawler, Dotbot. Moz’s Help Hub says Dotbot “is built on a machine learning-based model” trained “to start with high-value links,” and that newly discovered links should appear “within about 3 days of being found” (Moz Help Hub: How We Index the Web). Moz also says it tries “to re-crawl all high-quality pages at least every 90 days.”
There’s one practical catch. If a site’s robots.txt blocks Dotbot, or a linking page carries a noindex tag, Moz won’t display that data. Some site owners block SEO crawlers to save server load. If a site that links to you does that, Moz may never count the link.
Why the scale gets harder near the top
Why is it so much harder to go from 70 to 80 than from 20 to 30? Moz explains it with an example: if Facebook.com gained a billion new links, other sites’ DA would drop relative to Facebook’s. Large, heavily linked domains “take up more high-DA slots,” so the top of the scale is crowded. Moz’s conclusion is direct: “it’s easier to grow your score from 20 to 30 than it is to grow it from 70 to 80.”
For a small site, that’s good news. Your first few dozen quality links move the score more than any later batch will.
One Small Site, Four Tools: Authority Scores From 3 to 15
On October 21, 2026, four SEO tools gave the same small site authority scores of 3, 3, 7 and 15, per our test log. We looked up a small marketing website our own team runs in each tool, on a free account or a no-card trial, and copied the numbers from the screen.
| Tool and plan | Score shown | What the score is | Referring domains | Backlinks |
|---|---|---|---|---|
| Mangools SiteProfiler and LinkMiner (free) | Domain Authority 3/100, Page Authority 26/100 | Moz’s metrics, per Mangools | 40 | 2.4k active |
| Ubersuggest Backlinks Overview (free) | Domain Authority 3 | Moz data through the Moz API, per Ubersuggest | 48 | 1,860 |
| Semrush Backlink Analytics (free) | Authority Score 7, “Low authority” | Semrush’s own score | 46 | 2.7K |
| SE Ranking Backlink Checker (14-day trial) | Domain Trust 15/100, Page Trust 7/100 | SE Ranking’s own score | 77 | 2.2K |
Source: Indie Stack Lab test records for Mangools, Ubersuggest, Semrush and SE Ranking, October 21, 2026.
Why two tools agree on DA 3
The two 3s aren’t a coincidence. Mangools says SiteProfiler checks a site’s authority “with the well-known SEO metrics by Moz and Majestic” (Mangools SiteProfiler). Ubersuggest says it “sources data via the Moz API,” including “key metrics like Domain Authority and Page Authority” (Ubersuggest help center). So both tools were showing Moz’s Domain Authority, even though we never opened Moz itself.
What surprised us was that the referring-domain counts still differed: 40 in Mangools’ LinkMiner and 48 in Ubersuggest. Same DA, different link lists. One lookup can’t tell us why. What it does show is that a matching score doesn’t mean matching link data underneath it.
Why the other two read higher
Semrush and SE Ranking use their own link indexes and their own formulas, so their numbers sit on different scales. Semrush’s Authority Score mixes organic traffic and spam signals into its link measure. SE Ranking found the most referring domains of the four tools, 77, and marked 61 of them as new in the last 30 days.
Here’s our reading of it. On a site this small, every tool is counting a few dozen linking domains, so a gap of 30 domains between two indexes is a big share of the total. Scores swing more than they would on a large site. The 2023 study’s high agreement was measured on domains that appeared in Google results for 61 queries. On a tiny site, expect the tools to disagree by more.
So which number should you use? Pick one tool and stay with it. Our guide to using SEO tools without misreading their numbers shows the same split in keyword difficulty scores, and our roundup of cheaper SEO tools we tested as Semrush alternatives lists each tool’s free limits. For the individual tools, see what Mangools’ free account showed on a real site and what Ubersuggest’s free plan did on the same site.
Domain Authority vs Ahrefs DR vs Semrush Authority Score
Domain Authority, Ahrefs’ Domain Rating and Semrush’s Authority Score all use a 100-point scale, but each is built differently; Semrush’s, for one, combines eight weighted factors and is updated “once every two weeks” (Semrush Knowledge Base). Here is how each vendor describes its own metric.
| Metric | Made by | Scale | What it’s built from, per the vendor |
|---|---|---|---|
| Domain Authority (DA) | Moz | 1 to 100 | Machine learning on link data, mainly linking root domains and link quality |
| Domain Rating (DR) | Ahrefs | 100-point scale | Backlink profile strength compared with other sites in Ahrefs’ database; each linking domain splits its rating among the domains it links to |
| Authority Score (AS) | Semrush | 1 to 100 | Link power, organic traffic and spam factors |
| Domain Trust (DT) | SE Ranking | 1 to 100 | Number and quality of backlinks and referring domains, using PageRank principles |
If you’re comparing Ahrefs DR vs Moz DA for the same site, the table explains why the two numbers rarely match. They come from different crawlers, different link databases and different math.
Ahrefs Domain Rating
Ahrefs describes DR as showing “the strength of a website’s backlink profile compared to the others in our database on a 100-point scale” (Ahrefs help center). The twist is how link value gets shared: “The source domain splits its rating equally amongst the domains it links to.” So a DR-10 domain that links to three sites can move your DR more than a DR-80 domain that links to a million. Ahrefs also says DR “correlates with Google rankings pretty well,” but less well than its page-level URL Rating. Our guide to Ahrefs’ features, free tools and plans shows where DR appears in Site Explorer.
Semrush Authority Score
Semrush calls Authority Score its “compound metric that grades the overall quality of a website or a webpage,” on “a scale of 1 to 100.” Unlike DA and DR, it isn’t link-only. Its three facets are Link Power, Organic Traffic and Spam Factors, and six of its eight factors are spam checks, such as “Too many referring domains with the same IP address.”
In our test, the score arrived with the label “Low authority”. Semrush explains that label like this: “This domain has few backlinks. While there are no signs of manipulation, a link from this domain is unlikely to benefit your profile.” For a young site, that’s a fair summary. For the rest of that free account, see what a free Semrush account includes, task by task.
SE Ranking Domain Trust
SE Ranking scores Domain Trust from 1 to 100 by assessing “both the number and quality of backlinks and referring domains, using PageRank principles,” and says the scores “are updated multiple times each month” (SE Ranking Domain Trust checker). Its own page answers the DA question directly: the two metrics “use different methods and data, so the numbers may not match.” Honestly, that’s the most useful sentence on any of these pages. More in our write-up of what SE Ranking’s 14-day trial showed on a real site.
Do the scores agree?
For ranking sites against each other, mostly yes. The 2023 study in the journal Profesional de la información compared DA, Authority Score and DR for 3,151 domains, drawn from 16,937 results for 61 queries, and found pairwise Spearman correlations above 0.9 (Reyes-Lillo et al., 2023). The order of sites largely agrees; the absolute numbers don’t. A DA of 40 and a DR of 40 are not the same claim.
What Counts as a Good Domain Authority Score?
There’s no universal good score: Moz says “a DA of 30 might be exceptional in one industry but low in another” (Moz Learning Center). A good DA is one that’s close to, or above, the sites you compete with for the same searches.
Moz’s own FAQ gives two concrete anchors. New websites “always start with a Domain Authority of 1.” And if your competitors sit at DA 40 to 50, Moz suggests you “aim to reach or exceed that range.” Asked whether 20 is a good score, Moz answers “It depends,” adding that a DA of 20 “might be competitive for new or smaller websites.”
How to find your real benchmark
How do you find the right comparison set? Search your three most important keywords, note the domains on page one, and check their DA in one tool. Those are your competitors in Moz’s sense, whatever their size. If they sit around DA 25 and you’re at 12, you know the gap. Leave out huge general sites such as national newspapers. You aren’t competing with their whole domain, only with one of their pages.
Moz’s Help Hub recommends the same approach: compare your DA with competitors’, track the distance over time, and keep count of “how many linking root domains you have from index update to index update” (Moz Help Hub: How We Index the Web). That last number often explains a change faster than the score does.
What a low score does and doesn’t mean
Our test site sat at Moz DA 3. Does that mean Google won’t rank it? No. Google doesn’t use DA, and Semrush’s “Low authority” label described the same site as having few backlinks and “no signs of manipulation.” A low score on a young site is a starting point, not a verdict. It does tell you that link-heavy queries will be hard for now, and that useful content and internal fixes come first.
Why Your Domain Authority Changed: Updates and Fluctuations
Your DA changes when Moz finds new links or loses old ones: the index behind Link Explorer “is constantly updating,” and new links can appear “within about 3 days” (Moz Help Hub: Link Research). Moz adds that this “does not mean that DA and PA will change with every data update; they will only change if we find new links to a particular site.”
Moz’s Learning Center lists five reasons a score moves:
- Moz’s web index update includes more or fewer linking domains than the previous crawl.
- You gained or lost high-quality links.
- Other websites’ scores shifted, especially high-authority domains, which changes the relative scale.
- You earned links from sources that don’t contribute much to search rankings.
- Moz changed the model itself, as with the 2019 rollout of Domain Authority 2.0.
Why your score can drop without losing a link
Can your DA fall even if nothing changed on your site? Yes. Moz says DA and PA “are relative to the Internet as a whole”: if a large authoritative website “acquired a billion new links, everyone’s PA and DA would drop relative to that site” (Moz Help Hub: Link Research). Ahrefs says the same about DR: a DR 100 site can’t become DR 101, so when it gains links, “other websites are pushed down the scale.”
Links Moz can’t see
The other common cause is coverage. Links “will not drop out of the index due to age,” Moz says, but they show as Lost when Moz can’t find them on a recrawl (Moz Help Hub: How We Index the Web). A server error or a 404 at crawl time can also mark a link as lost, and Moz notes that “a lost link does not necessarily indicate that the link has been removed” (Moz Help Hub: Domain Overview).
So a sudden drop can be a crawl timing issue rather than a real loss. What should you do? Open the Discovered and Lost report and check whether the linking pages still exist. Then compare your linking root domain count across the next index updates, and look at whether your competitors moved too. If everyone dropped, it was the scale. If only you dropped and your linking domains fell, it was your links.
Bulk Checks, MozBar and Third-Party DA Checkers
Moz offers one official route for bulk checks: “The only way to check for Domain Authority, Page Authority or Spam Score in bulk would be our Links API,” per its Help Hub (Moz Help Hub: Link Research). The Moz API’s free tier allows “one request every ten seconds, up to 50 rows per month,” and paid plans start at $20/month (Moz API pricing).
For a short list, Link Explorer’s Compare Link Profiles view compares up to five sites, with a Metrics Over Time graph that defaults to Domain Authority over the last 12 months. Moz notes that Starter plans can compare 3 sites and “community accounts can compare only one competitor site” (Moz Help Hub: Compare Link Profiles). For the rest of Moz’s paid toolset, our guide to what each Moz Pro SEO tool does walks through it.
MozBar: DA while you browse
MozBar is Moz’s free extension for Chrome and Firefox. It shows Domain Authority, Page Authority, Brand Authority and the number of backlinks for sites as you browse and search (Moz Help Hub: MozBar Overview). Access comes in three levels, per Moz’s MozBar feature access guide:
| MozBar access level | What you need | Authority metrics, per Moz’s guide | Shared query limit |
|---|---|---|---|
| Login-free | No Moz account | No metrics bar, no SERP overlay | 0 |
| Community | Free Moz Community account | Limited metrics bar and SERP overlay: Domain Authority and Page Authority | 1,000 |
| MozBar Premium | Moz Pro free trial or paid plan | Full metrics bar and SERP overlay, plus Domain Overview and Ranking Keywords | 75,000 |
Each page visit uses 2 queries while MozBar is active, one for Domain and Page Authority and one for Brand Authority, and results for a URL are cached for 48 hours. By that math, a free Community account covers about 500 fresh page visits. If you search a lot, add busy sites you don’t need metrics for to MozBar’s Excluded Domains list.
Third-party “DA checker” sites
Search for a DA checker and you’ll find dozens of free sites. Some show Moz’s number; some show a formula of their own under the same two letters. Any site that shows Moz DA can only be as fresh as the Moz data it pulled. Ubersuggest, for example, says the data it gets from the Moz API “may be a few days old.”
Three checks before trusting one:
- Does it name its source? A “DA” with no mention of Moz may not be Moz’s metric.
- Does it show a date, or let you refresh the number?
- Does it match Moz? Spend one of your three free Moz reports on a site you know, and compare.
For free tools that show the actual link list and not just a score, see our comparison of free backlink checker tools.
How to Increase Moz Domain Authority Without Chasing the Number
Moz’s own answer is to improve your site’s overall SEO health “with a particular focus on the quality and quantity of external links pointing to your site” (Moz Learning Center). Every other tip on Moz’s list supports that one goal.
Moz’s list, in plain terms:
- Earn high-quality backlinks with content worth linking to: original research, expert guides and industry reports.
- Audit your link profile regularly and deal with spammy or harmful links.
- Optimize on-page SEO so content matches search intent.
- Improve user experience: page speed, mobile layout, navigation.
- Build a clear internal linking structure.
- Publish content that answers your audience’s questions.
Moz also lists what not to do. “Don’t buy backlinks” comes first, because bought links can lead to penalties from search engines.
Be honest about what moves DA
Here’s the catch. The model is link-centric. Page speed and internal links help visitors and Google, but they don’t feed DA directly; Moz’s Page Authority page says PA “does not take into consideration specific on-page elements like keyword use or content optimization,” and DA is built the same way at the domain level. Expect on-page work to help rankings directly and DA only through the links it attracts.
The same goes for removing bad links. Moz suggests you “identify and disavow spammy or harmful links.” Google’s own help page is more cautious: it calls disavowing “an advanced feature” and says “most sites will not need to use this tool,” mainly when links have caused or are likely to cause a manual action (Google Search Console Help). Disavowing to raise a Moz score is not a reason Google recognizes.
A sensible plan for a small site
What would we do with a site at DA 3? Not chase the number. Instead:
- Export the linking domains from one tool and read every row. On a small site, that’s a few dozen lines.
- Mark each one as real and related, real but unrelated, or junk. Leave the junk alone unless Google has flagged it.
- Find the pages that already earned links and update them, so they keep earning.
- Write one piece a month that someone in your niche would want to cite, such as a small dataset or a how-to with real numbers.
- Check DA once a month in the same tool, next to three competitors, and write the date beside each score.
If you blog, our guide to getting blog posts found in search covers the content side of that plan.
Page Authority, Spam Score and MozRank: The Related Moz Metrics
Page Authority (PA) is DA’s page-level twin: a 1 to 100 score that “predicts how well a specific web page will rank,” built from link counts and dozens of other factors, “more than 40 in total” (Moz: Page Authority). Moz calculates it “in the same way as Domain Authority but at the individual page level.”
Page Authority
In our test, Mangools showed a Page Authority of 26 next to a Domain Authority of 3 for the same site. Why can a page score higher than its domain? Moz doesn’t publish the weights, so we can’t say exactly why. What the gap does show is that PA and DA are separate models scored on separate sets of links, so don’t read one as a share of the other. Moz also puts PA on “a 100-point logarithmic scale,” the same rising difficulty as DA.
Spam Score
Spam Score “represents the percentage of sites with similar features we’ve found to be penalized or banned by Google,” per Moz’s MozBar guide, which adds: “This does not mean that the site is spammy.” It’s based on “27 common features,” and it is “not based on the links that are pointing to your site” (Moz Help Hub: Link Research). Moz’s checker page says “Any score lower than 30% is considered a low Spam Score.” Treat a high score as a reason to look closer, not as a penalty.
Brand Authority
Brand Authority is Moz’s newer score, a 1 to 100 measure of “the total strength of a brand,” and Moz notes it “is currently driven by US, UK, CA, and AU data” (Moz: Brand Authority). Where DA asks how strong a site’s links are, Brand Authority asks how strong the brand itself is.
Where MozRank fits
Many people still search for MozRank. In Moz’s current Page Authority documentation, “MozTrust + MozRank” appears in the list of factors behind PA, next to linking root domains, anchor text distribution and Spam Score. For one Moz number that describes a whole site, DA is the one that Moz’s checker, Link Explorer and MozBar all display.
Before You Report a Domain Authority Number: A Short Checklist
Before you put a DA in a client report or a pitch, run five quick checks; with 3 free reports a day from Moz’s checker (Moz Domain Authority Checker), you can cover your site and two rivals every day at no cost.
- Name the source. “Moz DA 3 (shown in Mangools)” says more than “DA 3.”
- Add the date. Scores move with every index update.
- Compare three to five competitors in the same tool.
- Show the linking root domain count next to the score.
- Never mix scales. Authority Score 7 and DA 3 don’t belong in one column.
Domain Authority is a useful shorthand for one question: how does this site’s link profile compare with its rivals’? Ask it that question and it answers well. Ask it whether Google likes your site, and it can’t.
Further Reading
- Four SEO suites run on the same website, with free-plan limits
- What four free SEO plans let you do
- How to use Google Search Console for SEO, including its links report
- How Ahrefs Domain Rating fits into Site Explorer and the Ahrefs plans
References
- Moz Learning Center: Domain Authority: What is it and how is it calculated
- Moz: Free Domain Authority Checker
- Moz Help Hub: Domain Authority Checker
- Moz: Link Explorer
- Moz Help Hub: Link Research
- Moz Help Hub: How We Index the Web
- Moz Help Hub: Compare Link Profiles
- Moz Help Hub: MozBar Overview
- Moz Help Hub: MozBar Feature Access Levels
- Moz Help Hub: Introduction to Domain Overview
- Moz: Moz API Pricing
- Moz Learning Center: Page Authority
- Moz Learning Center: Brand Authority
- Ahrefs help center: What is Domain Rating (DR)?
- Semrush Knowledge Base: What is Authority Score?
- SE Ranking: Domain Trust checker
- Mangools: SiteProfiler
- Ubersuggest help center: Ubersuggest is not showing all of my backlinks
- Reyes-Lillo, Morales-Vargas and Rovira (2023): Reliability of domain authority scores calculated by Moz, Semrush, and Ahrefs
- Google Search Console Help: Disavow links to your site