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Ahrefs SEO metrics

Backlink Metrics

Ahrefs has the most trusted backlinks data in the SEO industry (according to Aira’s State of Link Building Report):

  • 64% of SEO professionals trust Ahrefs’ link data over its competitors
  • 44% of SEO professionals use Ahrefs’ Domain Rating as their SEO metric of choice

We also have the #1 most active crawler in the SEO industry (according to CloudflareRadar) and our own search engine ( which helps us improve our crawling speed and breadth. It is precisely this technology that allows us to have the largest index of 35.0 trillion external backlinks.

In this lesson, we’re covering the following backlink metrics:

  • Backlinks and referring domains
  • URL rating
  • Domain Rating
  • Ahrefs Rank

Ahrefs’ SEO Metrics: Backlink-0

Backlinks and referring domains

The first two metrics are backlinks and referring domains.

The backlinks metric is a total count of all backlinks pointing at a target, while referring domains is the count of unique websites that point at a target.

The only data source required to calculate these numbers is our crawler.


These numbers will fairly go up and down in tandem as new links are discovered and dropped. Because of this, it’s perfectly normal for our backlinks and referring domains metrics to be different from other tools since we all crawl the web differently.

The total number of backlinks and referring domains is a so-called “bottom-level metric.” We use these to build more and more metrics like URL rating, which is our second link metric.

URL rating

Ahrefs’ SEO Metrics: Backlink-1

URL rating represents the overall strength of a page’s backlink profile ,measured on a logarithmic scale from 0 to 100.

If you’re familiar with Google’s PageRank (PR) formula, it should be easy for you to understand Ahrefs’ URL Rating since we use similar principles in our calculations. Those similarities include:

  • Counting links between pages
  • Looking at both internal and external links pointing at a target
  • Weighting the links differently
  • Respecting the “nofollow” attribute
  • Using a damping factor


While UR and PR are similar in nature, URL rating is not a direct replacement. Our algorithm is simpler compared to Google’s, which has evolved quite a bit over the years.

From our own studies, we’ve also found a clear positive correlation between URL rating and search traffic. This means that higher UR pages get more search traffic.

Ahrefs’ SEO Metrics: Backlink-2

Domain Rating

Ahrefs’ SEO Metrics: Backlink-3

Domain Rating represents the overall strength of a website’s backlink profile and considers both the size and quality of the links pointing at a website. Like UR, DR is also plotted on a logarithmic scale from 0-100.

To calculate DR, we use nearly the same principles as URL Rating, but we look at links between domains instead of pages. The more unique websites a site links to, the less so called “DR equity” it’ll transfer to each of them.

There are three main things to note when considering how DR is calculated:

  1. The number of unique referring domains that have at least one followed link pointing at the target website. This means that links that are nofollowed won’t improve DR for the target website. Subsequent links from the same website won’t help a website’s DR either, since referring domains only count one link per website.
  2. The DRs of the linking domains. For example, if a website has 1,000 followed referring domains from DR 0 websites, it’s unlikely that those links will help their pages rank. This also means that a website’s DR can increase if the Domain Ratings of the linking websites go up.
  3. The number of unique domains the referring websites link to with at least one followed link. The more unique websites a site links to, the less so called “DR equity” it’ll transfer to each of them.

    For example, if you were to get a link from the New York Times, which has a Domain Rating of 94, you might think that your DR should get a friendly little bump. That’s not necessarily true, since they also link to nearly 300,000 other websites with followed links.
    Ahrefs’ SEO Metrics: Backlink-4

    Getting a followed link from a site like DreamHost, which has a DR of 93 and links out to around 3,200 websites, would impact DR much more.


We don’t recommend using Domain Rating as a standalone metric.

It’s merely a measure of “link popularity” and not a good indicator of a website’s quality or legitimacy. A better practice is to pair DR with other metrics like domain level traffic or UR, which can give you a better feel of the quality of a link.

Ahrefs Rank

Ahrefs’ SEO Metrics: Backlink-5

Ahrefs Rank represents all websites in our database ordered by their raw DR values.

You can look at Ahrefs Rank as a much more granular version of Domain Rating, since it gives you the entire spectrum of DR across the web.


Ahrefs’ Rank doesn’t have anything to do with your Google rankings or search traffic. It also doesn’t directly affect your rankings.

Next lesson

Keyword and Search Traffic Metrics