Arguably, in 2025 link building remains one of the most challenging and one of the most impacting SEO activities.
Link building budgets continue to grow, understandably, and SEO marketers want to see this money well-spent.
But how do you know that your significant link building budget is well-allocated and your strategy has the efficiency you want?
In this article, we will discuss 15 crucial link building metrics that can help you get a very complete picture of how well your backlink profile is doing. Keeping an eye on these metrics allows you to quickly understand what’s happening, take swift corrective actions if necessary and plan for the future.
Metrics vs. KPIs: What’s the Difference?
Before we get down to the bottom of specific metrics, it’s important to distinguish between metrics and key performance indicators (KPIs) in the context of link building.
Metrics are raw data points that track various aspects of link building, such as the number of backlinks, referring domains, or anchor text distribution. They help monitor performance but do not necessarily indicate success.
KPIs (Key Performance Indicators) are metrics as seen in the context of your goals. As in, directly attached to your link building campaign goals. They reflect whether you have been successful or not. KPIs often include conversion-related metrics, such as referral traffic growth, ranking improvements over a period of time, or revenue generated from organic traffic.
Now, let’s break down the 15 most important link-building metrics to track in 2025 and how they influence SEO.
1. Total Backlinks
Definition: As is clear from its name, this metric shows the total number of backlinks pointing to your website.
Purpose: It basically indicates link-building activity and how many potential authority signals you have.
Impact: A higher number of backlinks can improve authority, but quality matters more than quantity.
There’s also a very important aspect of using this metric for SEO insights and strategy:
- Check how many total backlinks you have as compared to your direct competitors
- Check how this metric changes over time, between certain milestones to see the effect of this or that link-building technique
Verification: You can check this metric using Ahrefs, Moz, SEMrush, or Google Search Console.
Example: A website with 10,000 backlinks but from spammy sources may not rank as well as a site with 500 high-quality backlinks.
2. Referring Domains
Definition: The number of unique websites linking to your site. This metric differs from Total Backlinks. Where Total Backlinks takes into account every link leading from a particular domain, this one only accounts for unique domains. This is why it is always has a lower figure.
Purpose: You can use it as a strong signal of domain authority, as diverse sources show credibility.
Important: Your Total Backlinks and Referring Domains figures shouldn’t be more than 20-25 times apart ideally. A very large gap between the two can actually alert Google. For example, if you have a 1M total backlinks but only 100 Referring domains, it may be a clear sign to Google about manipulated backlink placement.
Impact: More referring domains, especially from authoritative sites, boost SEO more than multiple links from the same domain.
Verification: Tools like Ahrefs, SEMrush, and Majestic measure this.
Example: A site with 100 high-authority referring domains will easily outrank a site with 1,000 links from only five domains.
3. Domain Authority (DA) / Domain Rating (DR)
Definition: A score (0-100) predicting a site’s ability to rank based on link profile strength.
Purpose: If you’re looking this metric up for your site, it clearly tells you how you compare with your competitors in terms of ranking. If you’re looking it up for a potential backlink donor, it can help you evaluate how much link juice this linking domain can pass to you.
Impact: High DA/DR backlinks are more valuable than low DA/DR links.
TIP: Your DA/DR score can help you plan your keyword selection. The higher the score, the more it is possible for you to rank for keywords with a high difficulty rate. If you have a low DR score, you should first focus on less difficult more long-tailed keywords.
Verification: Moz (DA), Ahrefs (DR), and Majestic Trust Flow.
Example: A backlink from a DA 80 website (large scale mass media, auhoritative global portals) is much more valuable than a DA 20 blog.
4. Page Authority (PA) / URL Rating (UR)
Definition: A score (0-100) predicting a specific page’s ability to rank.
Purpose: Evaluates the strength of individual linking pages, not just domains. This ranking is highly useful when you’re researching content ideas and are doing a content gap research.
Impact: Understanding and comparing PA metrics for different pages allows you to pinpoint high-performers. This is a great way to know what strikes the cord with your audience better. It also helps you to see failing content strategies.
A tedious long-read How-To fails to capture audiences attention and has a low PA. But the same content wrapped in a series of short learning nuggets, videos and infographics does much better.
Verification: Moz (PA) and Ahrefs (UR).
5. Anchor Text Distribution
Definition: This metric analyzes clickable text used in hyperlinks pointing to your site. Devising proper anchor texts is a science in its own and anchor text distribution follows its own laws that you can use to your advantage or misuse and end up dealing with consequences. We have covered anchor text distribution in this article.
Purpose: A proper ratio of various types of anchor texts in your backlink profile helps you to create a natural backlink profile.
Impact: If your ratio of various types of anchor texts shows signs of manipulation, such as keyword stuffing, excess of direct matches, etc., it could trigger Google penalties.
Verification: Ahrefs and SEMrush provide tools for anchor text analysis.
Example: A natural anchor text distribution includes brand names, generic terms, and long-tail keywords. Here’s a recommended anchor text ration for a healthy backlink profile:
6. Dofollow vs. Nofollow Links
Definition: Dofollow links pass link equity (link juice) and are counted by Google against your SERP results. Nofollow links do not. Most social media links, for instance, are nofollow. You can also manually mark links as nofollow if they are obviously sponsored.
Purpose: A healthy balance of both prevents your profile from being considered spammy by Google. A 60:40 or 70:30 dofollow to nofollow link ratio has been recommended by most SEO specialists.
Impact: Dofollow links improve rankings, but nofollow links contribute to referral traffic. If your ratio looks askew, you may research it. For instance, a larger than usual quantity of nofollow links can mean you’re trending on social media but aren’t capitalizing on it.
Verification: Chrome extension “NoFollow” or Ahrefs.
Example: A dofollow link from a niche-relevant blog is more valuable than a nofollow social media link. But a nofollow link from a huge social media account may generate a great amount of referral traffic which can subsequently lead to organic backlinks and brand mentions.
7. Link Diversity
Definition: This metric is not so set in stone and can be arguably estimated. It refers to a variety of different types of backlinks pointing to your site, including guest posts, forum links, editorial mentions, directory listings, and social media shares.
Purpose: A diverse backlink profile usually means your backlinks were acquired naturally or in a way passing as natural. This is always a good signal for Google and for you it reduces the risk of being flagged as a manipulative actor.
Impact: Sites with varied link sources and a higher number of distant root domains tend to perform better in rankings compared to those relying on only one type of backlink or their backlinks are coming from very similar sources.
Verification: Analyze link profiles using Ahrefs, SEMrush, or Google Search Console to categorize links. This can’t be as a set metric, but rather as an array of analytic data.
Example: A site with 90% guest post backlinks and 10% other sources may look artificial, while a site with a mix of editorial, guest post, and natural mentions appears more credible.
8. Link Relevance
Definition: The topical relevance of the linking site to your niche, but that’s putting it simply. In fact, there are a lot of aspects to relevance. It all boils down to making your link look natural in the context of where it is placed. Check out our detailed guide to relevant link building!
Purpose: Relevance is one of the highest-impacting factors when Google estimates the value of a link.
Impact: Irrelevant links may be ignored by Google or even trigger penalties if you’re using them in bulk.
Verification: Google uses a very complicated algorithm it doesn’t disclose when it comes to estimating relevance. You can opt for E-E-A-T and YMYL principles when assessing link relevance and use Majestic’s Topical Trust Flow.
Example: A backlink from a fitness blog is more relevant to a health supplement store than one from a car repair website.
9. New vs. Lost Backlinks
Definition: This is an important dynamic metric which tracks links gained and lost over time.
Purpose: A healthy backlink profile is a growing, moving thing and it should never be viewed statically. Some of the most important backlink analysis metrics reflect its dynamic changes.
Impact: A sudden drop in backlinks can indicate a penalty or deindexing.
Verification: Ahrefs, SEMrush, and Google Search Console.
Example: A loss of 50% of backlinks after a Google update might indicate that you have been slapped with an algorithm penalty and a lot of your older links are now considered low-quality.
10. Spam Score / Toxicity Score
Definition: This rating helps you to predict whether a link from a potential prospect site will be valuable or may even be detrimental. One of the more important metrics you should always check your source domains for.
Purpose: Helps avoid penalties from low-quality links.
Impact: High spam scores reduce SEO value and may trigger Google penalties.
Verification: Moz Spam Score, SEMrush Toxic Score.
Example: Links from PBNs (Private Blog Networks) often have high spam scores.
11. Citation Flow & Trust Flow
Definition: In a very few words, Citation Flow (CF) measures link quantity, Trust Flow (TF) measures quality. If you would like to dive deeply into what these two metrics represent and what is their true value for your SEO, we have a very detailed guide here.
Purpose: Helps you to understand whether there’s a balance between link volume and credibility. There’s a connection between the two, as seen on the image above, and you correlation between TF and CF shouldn’t be askew.
Impact: High TF is better than high CF with low TF.
Verification: Majestic SEO.
Example: A site with CF 50 and TF 20 likely has spammy links and it will be evident to Google, so if it’s your site, you should take action. If you’re considering getting a backlink from this site, maybe you should reconsider.
12. Indexation Status of Backlinks
Definition: This metric shows whether search engines have indexed the page containing your backlink. Until they do, the backlink is useless.
Purpose: Google only counts backlinks from indexed pages towards SERP rankings. Since it is up to webmasters to allow Google to index certain pages, it’s something you should check before arranging a link placement.
Impact: Unindexed links provide no SEO value.
Verification: Google Search (“site:[URL]”).
Example: If we want to see whether google has indexed our blog article or not, we can check it using this search query:
site:serpzilla.com/blog/understanding-trust-flow-and-citation-flow-how-to-increase-your-site-credibility/
If it appears in search results, it is indexed.
13. Domain Age of Referring Sites
Definition: Another important metric you should always check when researching your backlink prospects. It denotes the length of time a referring domain has been active and indexed by search engines.
Purpose: Older domains tend to have more authority and trust compared to newly registered domains, making backlinks from them more valuable.
Impact: This is especially relevant if you’re getting a link from a domain network. It’s pretty simple to make a domain look old, for instance, a blog can easily manipulate the publishing dates of its entries, especially if it’s not using a common blog platform. It’s easy to miss out on a backlink value if you don’t research this metric properly.
Verification: Use tools like Whois Lookup, Ahrefs, or Wayback Machine to check the domain’s registration date and history.
Example: A backlink from a 15-year-old industry blog is more valuable than one from a 1-month-old niche site that may disappear quickly.
14. Ratio of Inbound vs. Outbound Links
Definition: This is an important metric you should check for your link prospects as well as for your site, if you’re giving out backlinks too. It’s the proportion of backlinks a referring site receives compared to the number of links it gives out.
Purpose: Using this link you can check that a site linking to you isn’t overly diluted by excessive outgoing links. This type of disproportion in this ratio can signify a much lower backlink value than other metrics may suggest.
Impact: Websites with a healthy balance of incoming and outgoing links tend to pass more SEO value. The thing is, the link equity a site can pass is a finite value and is divided between all the links. If outbound links heavily outweigh inbound ones, it can still only give out as much value as it gets. Spread too thin like that, each link will get very little.
Verification: Use Ahrefs Site Explorer or Moz to analyze the link profile of referring domains and their link distribution.
Example:
- A backlink from a high-authority blog that links to only a few external sites is more valuable than one from a directory or low-quality site that links to thousands of pages.
- If a website has 10,000 outgoing links but only 500 incoming links, its credibility may be lower, signaling a potential link farm rather than a reputable source.
Conclusion:
Analyzing what you do right and wrong and what your competitors do right and wrong is key to improving your link building strategy. The 15 link building metrics described above can be used to gather extensive, precise and multifaceted data for your analysis.
Using these metrics, you can research your link prospects to get only the most useful and relevant links, check up on your own link profile and see what your competitors are doing better or worse. The key takeaway? Link building isn’t just about acquiring links—it’s about acquiring the right links.
