Why Ahrefs, Semrush, Moz and Majestic show different backlink numbers
Each backlink tool runs its own crawler, keeps its own index and applies its own rules for what counts as a live link. None sees the whole web, so the same site gets different totals in every tool. Pick one tool for comparisons and use a second only to widen coverage.
In short
- In October 2026 Ahrefs claimed an index of 35 trillion external backlinks, Semrush more than 43 trillion backlinks and Moz 45.5 trillion links, each on its own website and each counted in its own way.
- Majestic keeps two indexes, a Fresh Index covering about the last four months and a Historic Index going back to 2006, and they return different totals for the same site.
- Google's Search Console help page says its Links report is a sample and is not a full list, so it does not settle which tool is right.
- Private networks and some publishers block third-party crawlers, so every tool under-reports parts of the web, and grey-market profiles most of all.
- Scores from different tools cannot be compared, so use one tool for every site in a comparison.
Backlink tools disagree because each one builds its own copy of the web’s links. Ahrefs, Semrush, Moz and Majestic each run a crawler, store what it finds in a private index and apply their own rules for what counts as a link, a duplicate or a lost link. No crawler reaches every page, so each index is a different, incomplete sample.
None of the numbers is wrong and none is the truth. They are different measurements. Once you know why they differ, you can decide which one to use for which job.
Each tool crawls its own web
A backlink tool finds links the way a search engine does: by fetching pages and following the links on them. What ends up in the index depends on choices the vendor makes.
- Where the crawl starts and what it favours. A crawler that favours popular sites finds links on news sites quickly and may never reach a small forum.
- How often it returns. A link added yesterday shows up in one tool today and in another next month.
- What blocks it. Site owners can block any crawler in robots.txt or at the firewall. Private blog networks often block the SEO tool crawlers on purpose so competitors cannot see them.
- Whether it renders JavaScript. Links added by scripts are invisible to a crawler that reads only the raw HTML.
The research behind our iGaming hub cites a 2026 ICODA article which reports that grey-market gambling sites rely on networks that block Ahrefs and Semrush bots, so the tools under-report those profiles. The same applies, to a lesser degree, in every market.
What the vendors claim
The figures below were read on each company’s own website on 4 October 2026. They are marketing claims and are not counted the same way, so they cannot be ranked against each other.
| Tool | Published index claim | Stated freshness |
|---|---|---|
| Ahrefs | 35 trillion external backlinks and 493.9 billion pages in its index | Backlink index updated every 15 to 30 minutes |
| Majestic | Fresh Index of about 184 billion unique URLs crawled, covering 6 June to 3 October 2026. Historic Index of about 4.5 trillion URLs crawled since 2006 | Fresh Index updated within the last few hours when we looked. Historic Index showed a last update in May 2024 |
| Moz | 45.5 trillion links, 8.7 trillion URLs and 1 billion domains in Link Explorer | Not stated on the page |
| Semrush | More than 43 trillion backlinks and 390 million referring domains | Database refreshed at least hourly |
Two things stand out. First, “links” in one row may include historical records, internal links or duplicates that another vendor leaves out, and the pages do not always say. Second, Majestic counts URLs crawled where the others count links, so its row is not on the same scale at all.
Our Semrush desk review and Moz desk review record what each vendor publishes about its data.
Live, fresh and historic are different things
A large part of the gap between tools comes from time.
Majestic makes this explicit by offering two indexes. The Fresh Index covers roughly the last four months. The Historic Index goes back to 2006. A site checked in both gets two very different totals, and both are correct for what they describe.
Other tools make similar choices less visibly. A link that was live last year and has since been deleted may be shown as live, shown as lost, or dropped from the report, depending on when the crawler last visited and how the tool treats links it has not rechecked. Links disappear all the time: an Ahrefs study dated February 2024 found that 66.5% of links to about two million sites had rotted since January 2013. How long backlinks last covers that in detail. A tool that rechecks slowly will carry more dead links in its totals.
Counting rules differ
Even when two tools have crawled the same pages, they can report different numbers.
- Backlinks or referring domains. One sitewide footer link can be thousands of backlinks and a single referring domain. Totals of backlinks vary far more between tools than totals of domains.
- Duplicates. The same article at several addresses, such as with and without a tracking parameter, may be counted once or several times.
- Domains and subdomains. A blog platform with thousands of subdomains can be one referring domain or thousands.
- Redirects and canonicals. A link to an old address that redirects to you may be credited to you or not.
- Nofollow and other attributes. Some headline numbers include every link and some only followed links.
- Filtering. Tools may hide links they judge to be spam or to come from pages of no value.
Scores differ for a second reason
Authority scores sit on top of these indexes and add a formula. Domain Rating is Ahrefs’ calculation of link strength. Domain Authority is Moz’s machine-learned prediction of ranking. Semrush’s Authority Score combines links with organic traffic and spam checks. Majestic’s Trust Flow measures closeness to a trusted seed set.
Different data plus different formulas means the same site can be DR 60, DA 40 and Authority Score 35 on the same day. Authority metrics explained covers what each one measures. When a seller quotes a score, ask which tool it came from and check it there.
Google is not the referee
It is tempting to treat Search Console as the true count. Google’s help page for the Links report says otherwise: the report shows a sample, tables stop at 1,000 rows, and it “isn’t a comprehensive list”. Duplicate links from the same source page to the same target are merged.
Search Console also only works for sites you have verified, so it cannot help with competitors. And it does not say which links Google counts, only which ones it has seen.
What to do about it
This is a working method.
- Choose one primary tool and use it for every comparison between sites. A gap of 200 referring domains means something inside one tool and nothing across two.
- Compare referring domains, not backlinks. Domain counts are less distorted by counting rules.
- Watch trends, not absolutes. A rising or falling line inside one tool is more reliable than any single total.
- Test coverage in your own market. Take three sites whose links you know well, such as your own, and see which tool finds the most of them. Coverage of smaller languages varies a lot.
- Merge sources when completeness matters. For a backlink audit, combine exports from two tools and Search Console and remove duplicates.
- Check traffic estimates the same way. A 2026 guide from Setproduct treats a spread of about two times between tools as normal and a spread above five times as a sign of manipulation. That is a rule of thumb, not a measured threshold.
- Verify the links that matter by hand. For placements you paid for, open the page. Tracking backlinks describes the checks.
Where to go next
The backlink tools comparison lists the tools with their plans and limits. If a competitor’s profile looks too small for its rankings, hidden private blog networks are one possible reason. Terms such as index, crawler and referring domain are defined in the glossary.
Common questions
Which backlink tool is the most accurate?
No independent test we could find settles this. Each vendor publishes its own index size, counted in its own way. Accuracy also varies by country and language, so test the tools on a few sites you know well.
Why does Ahrefs show more backlinks than Semrush, or the other way round?
The crawlers visit different pages on different schedules, and the tools use different rules for duplicates, redirects, lost links and history. Either can be higher for a given site.
Why does Google Search Console show different numbers from every tool?
Search Console reports a sample of the links Google knows about and merges duplicates. Third-party tools crawl independently, so they find some links Google does not list and miss others.
Should I use more than one backlink tool?
For comparing sites, use one. For building the fullest possible list of your own links, for an audit or a disavow file, merging exports from two tools and Search Console finds more.
Why is my Domain Rating different from my Domain Authority?
They are different formulas run on different indexes. Domain Rating is Ahrefs' link-strength calculation and Domain Authority is Moz's ranking prediction, so the numbers were never meant to match.
