Link building metrics: what to check before a link and what to read after

Link building metrics are the scores and counts published by four tool makers that describe a site's links: Moz's Domain Authority, Page Authority and Spam Score; Ahrefs' Domain Rating, URL Rating, referring domains and organic traffic estimate; Majestic's Trust Flow and Citation Flow; and Semrush's Authority Score. Each maker says its score is for comparing sites with each other, not for grading one site on its own.

This page gives each metric in its maker's own words, with the page named beside it and its date where the page gives one, and then splits the ten into two working groups: the numbers to check before taking a link from a site, and the numbers to read after the links are live. It ends with what we read when we vet a site. Moz's Domain Authority, the DA metric for link building, comes first in the table and in the checks before a link, and the other link metrics for SEO follow it, because no single number describes a site on its own.

The ten link building metrics and who publishes them

Ten metrics for link building make up the working set, and the table below gives each metric's publisher, scale and what it describes.

Each scale is its maker's own, worked out against its maker's own index, so a DA and a DR are never the same number in a different coat. The full comparison of the two most used scores is in DA vs DR, and our free DA and DR checker reads both for any domain.

Metrics to check before taking a link from a site

These are the numbers read when choosing a site, before any link is placed, each given in its maker's own words with the page named, and its date where the page gives one.

Domain Authority. Moz's Learn page on Domain Authority, last updated 18 March 2025, defines the score: "Domain Authority® (DA) is a search engine ranking score developed by Moz. It predicts how likely a website is to rank on search engine results pages (SERPs) compared to competitors. The score ranges from 1 to 100, with higher scores indicating a greater ability to rank." On how to use the score, the same page says: "The best way to use DA is to compare your score to competitors in your industry." Moz states on that page that Domain Authority is not a Google ranking factor and has no effect on the SERPs, and that there is no universal good or average score because the metric is relative. Read that way, a DA figure only means something next to the scores of competing sites. The full write-up of the score is in the Moz DA guide.

Domain Rating. Ahrefs' help page on Domain Rating, written 3 September 2026, defines the score: "Domain Rating (DR) shows the strength of a website's backlink profile compared to the others in our database on a 100-point scale." The same page gives the intended use: "Instead, consider DR as a great metric for selecting websites to build links from." And it gives the caution: "You should never judge the quality of a website on site-wide "authority" alone." The questions the page lists next include whether the site gets any organic traffic and whether it is topically relevant to yours. Ahrefs' Academy page on backlink metrics adds: "We don't recommend using Domain Rating as a standalone metric." and recommends pairing DR with domain-level traffic or URL Rating. Ahrefs' help page on whether search engines use Domain Rating, dated 3 September 2026, states there is no evidence that they use it, or similar scores such as Domain Authority, as a ranking factor. Read together, the Ahrefs pages set DR as a shortlisting tool: strong enough to sort a list of candidate sites, not enough to pass one on its own. The reports behind these numbers are walked through in how to use Ahrefs for link building.

Page Authority and URL Rating. Moz's Learn page on Page Authority, written 18 November 2024, defines the score: "Page Authority (PA) is a score developed by Moz that predicts how well a specific web page will rank on search engine result pages (SERP). Page Authority scores range from one to 100, with higher scores corresponding to a greater ability to rank." Ahrefs' help page on URL Rating, written 3 September 2026, gives the Ahrefs page-level score: "URL Rating (UR) shows the strength of a page's link profile on a 100-point scale." The same page draws the line between the two levels: "UR is a page-level metric, whereas DR is a domain-level metric." Where DA and DR describe the whole site, PA and UR describe one page. For a link placed in one article, the page's score is the one that describes where the link sits.

Referring domains and backlinks. Ahrefs' help page on referring domains, written 3 September 2026, defines the term: "Referring domains are domains from which the target website or web page has one or more backlinks." Ahrefs' Academy page separates the two counts: "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." Moz, Majestic and Semrush count linking domains too, and ten links from one site count as one referring domain. A backlink total can grow while the referring domain count stands still, so the two counts answer different questions. How many referring domains a page needs is a different question again, answered in how many backlinks do I need to rank.

Organic traffic. Ahrefs' help page on organic traffic, written 3 September 2026, defines the metric: "The Organic traffic metric in Ahrefs is an estimation of how many clicks from google your target website, subfolder or URL gets each month." The estimate is built from the keywords a site ranks for, its position for each, the monthly search volume and an estimated click-through rate for that position, all summed. The same page warns: "NOTE: Remember to treat the organic traffic estimations in Ahrefs as precisely that: estimations." One sampled set of figures from the same maker, built from actual clicks rather than estimates, shows how far traffic differs between DR bands: Ahrefs' organic traffic benchmarks page, dated 23 June 2026, draws on anonymised Search Console data for 344,956 websites in June 2026. In that sample, the median site in the 0 to 10 DR band had 9 organic clicks in the month, the median site in the 50 to 60 band had 1,594, and the median site in the 90 to 100 band had 81,530. The page's own caution reads: "DR is a proxy for the authority that wins traffic, not a dial you turn to get it." For choosing a site, the estimate answers a plain question: whether the site gets any search traffic at all.

Trust Flow and Citation Flow. Majestic's help glossary defines the pair: "Trust Flow, a trademark of Majestic, is a score based on quality, on a scale between 0-100." and "Citation Flow is a score between 0-100 which helps to measure the link equity or "power" the website or link carries." Majestic's page on Flow Metric scores sets the intended use: "Flow Metric scores are intended for use in like for like comparisons" and states that comparing the Trust Flow of a page against the Trust Flow of a whole site is not advisable. Read side by side, Citation Flow reflects how many links a site has, and Trust Flow reflects how closely those links connect to Majestic's reviewed seed set. The pair is explained in full in Trust Flow vs Citation Flow.

Authority Score. Semrush's Knowledge Base page on Authority Score defines it: "Authority Score is our compound metric that grades the overall quality of a website or a webpage." The same page sets the use: "Authority Score is best used for domain comparison, and not for determining good/bad on an absolute scale." The page says the score is updated for all domains once every two weeks. Because Authority Score folds overall quality into one number, Semrush's own guidance keeps it to comparing domains rather than grading one.

Spam Score. Moz's help page on Spam Score says the score is per site, built from a machine-learning model of 27 signals found on a site, updated quarterly, and read in three bands: 1% to 30% low, 31% to 60% medium and 61% to 100% high. The same page asks whether Spam Score is a calculation of the Spam Score of the sites linking to you, and answers: "No, it's not." Moz describes its use as a guide for starting an investigation rather than a verdict, so a band is a prompt to look closer, not a decision. The topic has its own page: website spam score.

Anchor text and link attributes

Two things on the linking page are read alongside the scores: the anchor text and the link's rel attribute. The anchor text is the clickable wording of the link, and on an ordered placement the buyer supplies it. The rel attribute can mark a link as nofollow or UGC, and a link with no such value is what tools call dofollow. Both topics have their own guides: anchor text and dofollow vs nofollow backlinks.

Reading a profile by attribute shows what the totals hide. Christian Ott is an SEO consultant who publishes figures for his own site. His one-year review of that site, published 9 July 2026 and updated 26 September 2026, sets out his counts: "Ahrefs (free) counts 343 backlinks - but only 163 of them are dofollow, 182 are nofollow and 3 are UGC (measured in Ahrefs)." He draws the lesson from his own list: "Anyone who sorts their link profile by domain rating and then feels proud should take a look at who is actually linking." Those are one site's counts, measured in one tool, and the point is the habit of opening the list.

Metrics to read after the links are live

The first group of after-metrics is referring domains over time. A new link appears in a tool when the tool's crawler finds the page, and the wait varies: Ahrefs' help page on the time it takes to find a new backlink, written 3 September 2026, says "it can take a few days up to some weeks before we crawl your new backlink". Ahrefs' help page on the links database, also written 3 September 2026, says the index is updated with fresh data every 15 to 30 minutes, while a complete refresh of the whole database takes about two months. A link that leaves the report may be tagged Dropped, and the help page on dropped links, same date, defines the tag: "Dropped are links from pages that were removed from our index due to various reasons." The full read of a profile, lost links included, is in link audit.

The second group is the scores over time. Moz's Learn page on Domain Authority, last updated 18 March 2025, says Domain Authority is dynamic and changes over time, and Moz's Page Authority page says including PA in reporting can help decision-makers understand the results of link building work. A score moves slowly and relative to every other site in the index, so a flat score is not a flat result.

The third group is traffic trends. Ahrefs' help page on organic traffic, answering why its figure differs from Search Console, is plain about what the tool shows: "The number that Ahrefs shows is an estimate, not the actual search traffic data of a website." A second help page, on organic traffic against Analytics and Search Console, written 3 September 2026, gives the intended use: "Marketers use this data to compare websites with one another and see the trends in organic traffic (if the website is growing or losing traffic)." For your own site, your own property's figures in Analytics and Search Console are the ones to read.

The last group is rankings, referral visits and return. Tagging a placed link so a visit is filed under it is covered in UTM link building, and turning rankings and visits into a return figure is covered in measuring link building ROI.

What we read when we vet a site

For Guest Posts, Moz DA sets the tier and the price, because the higher the score, the stronger the site's link profile. Ahrefs DR and live traffic tell us whether that number is earned. We read indexed pages, organic traffic and its trend, Moz DA, Ahrefs DR, referring domains and the link profile together, weighed as a set rather than as one score. A site whose scores look strong but whose traffic does not hold up is turned away: a high DA figure on an empty site is still an empty site.

For Curated Links, sites are chosen on relevance, referring domains, DA, organic traffic and overall site quality, and the tier is set by referring domains. You supply the anchor text and the target URL, and branded and partial anchors are often the most suitable.

After publication we check that the page is live, that the link sits in the body copy, that the anchor text and target URL match the order, and that the page is indexable. Only then is the URL reported to the dashboard, where it can be exported as an unbranded file. Every delivered link has 12-month replacement cover. The full standard is on our quality assurance page.

Frequently asked questions

What are link building metrics?

Link building metrics are the scores and counts that four tool makers publish to describe a site's links. The ten are Moz's Domain Authority, Page Authority and Spam Score; Ahrefs' Domain Rating, URL Rating, referring domains and organic traffic estimate; Majestic's Trust Flow and Citation Flow; and Semrush's Authority Score. Each maker says its score is for comparing sites with each other, not for grading one site on its own.

What DA or DR should a site have before I take a link from it?

No fixed reading of DA or DR exists. Moz states there is no universal good or average Domain Authority score because the metric is relative, and Ahrefs states a Domain Rating cannot be called good in absolute terms. Both makers say to compare a site's score against others in its field, and Ahrefs recommends pairing the score with domain-level traffic or URL Rating before deciding.

Which link building metric matters most?

No single number is the best metric for link building on its own, because each maker says its score is built for comparison. Beside DA or DR, the two counts worth reading are referring domains and the organic traffic estimate. When we vet a site, we weigh indexed pages, organic traffic and its trend, Moz DA, Ahrefs DR, referring domains and the link profile together, and a site whose traffic does not hold up is turned away.

How do you measure link building success?

Link building success is measured in four groups of numbers read after the links are live: referring domains over time, the scores over time, traffic trends, and then rankings and referral visits. Ahrefs says a new link can take a few days up to some weeks to appear in its index, and a score moves slowly and relative to every other site in its maker's index, so a flat score is not a flat result. For your own site, your own property's figures in Analytics and Search Console are the ones to read.

What is the difference between DA and DR?

Domain Authority is Moz's score on a 1 to 100 scale, and Moz says it predicts how likely a site is to rank compared with competitors. Domain Rating is Ahrefs' score on a 100-point scale, measuring the strength of a site's backlink profile against the other sites in the Ahrefs database. Neither maker claims a search engine uses its score, and both makers say the scores are for comparison rather than absolute readings.