Website Authority Comparison Guide
SEO tools have developed metrics called domain authority to evaluate the strength of a website’s backlink profile.
Moz introduced its Domain Authority (DA) metric in 2004, and soon after, other SEO tools developed their own versions of “authority” metrics.
These metrics aim to assess a website’s potential to rank on Google Search.
Initially, the sheer number of backlinks to a website was considered the most crucial factor for ranking. However, these metrics have advanced to incorporate aspects such as the quality of the referring domains, spam scores, and organic traffic contributions.
The primary domain authority metrics in the industry are Moz DA, Majestic TF, Ahrefs DR, and Semrush AS.
Quick Comparison Table
| Parameter | Moz DA | Majestic TF | Ahrefs DR | Semrush AS |
|---|---|---|---|---|
| Measures backlink strength | ✔ | ✔ | ✔ | ✔ |
| Logarithmic (or non-linear) ranking scale | ✔ | ✔ | ✔ | ✔ |
| Considers authority of referring domains | ✔ | ✔ | ✔ | ✔ |
| Accounts for link equity | ✔ | ✔ | ✔ | ✔ |
| Assesses quality of links and referring domains | ✔ | ✔ | ✔ | ✔ |
| Considers organic traffic | ✖ | ✖ | ✖ | ✔ |
| Rapid and extensive backlink discovery | ✖ | ✖ | ✔ | ✔ |
| Difficult to manipulate | ✖ | ✖ | ✖ | ✔ |
What These Authority Metrics Share
Measures Backlink Strength
Backlinks are links from other sites that point to your website. The greater the number of backlinks, the more credible your site appears and the higher it is likely to rank on Google.
Authority metrics assess the overall strength of a website’s backlinks. Viewing backlinks as “votes,” these metrics gauge a site’s “popularity.”
As SEO tools have evolved, the focus has shifted from merely counting links to a more sophisticated approach.
Authority metrics now consider the quality of the links, the link equity, the authority of the referring domains, among other factors—elements that we will explore in more detail shortly. Still, at its core, the metric evaluates the strength of a site’s backlink profile.
Ranks Websites on a Logarithmic (or non-linear) Scale
These metrics assess websites on a logarithmic scale from 0 to 100, where 100 represents the highest backlink strength.
Both Semrush and Ahrefs clearly state that their scoring is logarithmic, while Majestic describes it as non-linear.
This logarithmic scaling implies that it becomes increasingly difficult to raise the authority score as it rises—for instance, improving from a score of 1 to 3 is significantly easier than from 71 to 73.
This scaling results in hundreds of millions of websites having an authority score below 10, with only a few reaching near 100.
Considers the Authority of the Referring Domains
No metric solely counts the number of backlinks or referring domains to a site.
Links from different sources carry varying weights.
For example, a link from a site with an authority score of 80 is more influential than one from a site scored at 20.
Accounts for Link “Juice”
Link juice refers to the value or authority that a referring domain transfers to a site through its link.
Link juice is a critical factor in all domain authority metrics.
A website that links to many other sites will transfer less link juice than a site of similar authority that links to fewer sites.
Consider this: a site with an authority level of 20 that links to only ten other domains will transfer more link juice than a site with an authority of 80 that links to millions of domains.
Quality of Links
All authority metrics now claim to assess both the quality of links and the presence of spam signals.
Due to their susceptibility to manipulation, SEO tools have evolved to combat efforts to game these metrics.
Semrush, for instance, considers spam factors such as:
- Lack of organic rankings on SERPs
- An unnaturally high percentage of do-follow domains
- A mismatch between the number of links and organic traffic
- Excessive referring domains from the same IP address or network
- Similar backlink profiles across different domains
Since 2019, Moz has enhanced its DA metric to better gauge link quality and spam, integrating multiple factors into its calculations.
Majestic focuses on quality, considering links only from reputable sites for its Trust Flow (TF) metric, while its Citation Flow (CF) measures the raw strength of backlinks.
Ahrefs emphasizes that its Domain Rating (DR) metric evaluates both the quantity and quality of links.
Ultimately, all metrics now prioritize the quality of links over simple backlink counting, recognizing that quality is a more crucial factor than quantity.
Are these claims genuine? To some extent, yes, but also no. More on manipulation shortly.
Organic Traffic
Until now, the focus has been primarily on link-related metrics such as link authority, link juice, and the quality of referring domains. However, organic traffic introduces a non-link metric.
Excluding organic traffic from authority metrics can lead to significant manipulation. True authority is relevant only with significant and relevant rankings on Google within a site’s niche. A site scored at 80 in authority but with negligible traffic in its niche lacks real authority.
If authority metrics do not consider or reflect a site’s organic traffic, they can be deemed manipulative and unrepresentative of genuine authority.
Including organic traffic in the authority metrics offers a more comprehensive view of a site’s standing from Google’s perspective.
Among the major metrics, only Semrush’s Authority Score (AS) includes a site’s organic traffic, aiding in mitigating authority manipulation, which will be explored in further detail.
Discovering Backlinks
When calculating domain authority, not all backlinks are accounted for. No SEO tool, including Google, captures every backlink.
The accuracy and timeliness of backlink discovery are crucial for the reliability of the authority metrics. If an SEO tool is slow to identify new links, taking weeks or even months, its authority metrics won’t accurately reflect the site’s current standing, thus losing its practical utility for tracking progress.
Our experiments aimed to evaluate the frequency of backlink discovery by various SEO tools revealed that Semrush and Ahrefs are more efficient at identifying new referring domains than Moz and Majestic.
Further testing showed disparities in the number of referring domains each tool discovered for the same websites, with Semrush consistently identifying more referring domains across a wider range of sites.
This ability to discover more backlinks enriches the domain authority calculation, providing a more comprehensive dataset about the site’s backlink profile.
While no tool can identify every backlink, Semrush appears to be the leader in incorporating the most backlinks into its Authority Score (AS) calculations, followed by Ahrefs.
Resistant to Manipulation
Most Domain Authority metrics are susceptible to tampering.
An entire industry of freelancers exists who specialize in artificially boosting site authority metrics through link spamming.
In our research, we explored how these metrics can be manipulated. We employed five freelancers to increase the authority scores for five different domains, with fees ranging from $15 to $80, totaling $275 for all services.
One particular domain, DRvsASExperiment.com, was targeted for all metrics, while the others were manipulated solely for Ahrefs’ DR.
After a waiting period of two months, here are our findings:
Ahrefs’ DR proved to be the most susceptible to manipulation. Although Moz’s DA and Majestic’s TF are also vulnerable, they are not as easily influenced as Ahrefs’ DR.
Semrush emerged as the most robust and tamper-resistant authority metric. Its Authority Score (AS) was not easily inflated, underscoring its reliability.
All the tested domains lacked content, had no traffic, and did not rank for any keywords. Despite this, their authority metrics varied, highlighting potential reliability issues unless using Semrush’s AS.
Which Is the Best Authority Metric?
While any authority metric, be it Moz’s DA, Majestic’s TF, Ahrefs’ DR, or Semrush’s AS, can track your website’s progress or benchmark against unmanipulated sites, Semrush’s AS stands out for several reasons:
- Semrush’s AS is the only metric that incorporates organic traffic, enhancing the reliability of its assessments of link quality and spam factors.
- Our research indicates that Semrush not only discovers the most backlinks but does so more quickly than its competitors.
- Semrush’s Authority Score is the most tamper-proof among the evaluated metrics, making it the most dependable measure for those seeking a genuine appraisal of site authority.
