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What are Site Focus and Site Radius metrics?

Updated on: 2026-01-22  
(9 min. read)
What are Site Focus and Site Radius metrics?
For years, topical authority in SEO functioned mainly as an intuitive concept, based on observation and experience. It was noticed that websites with strong topical authority perform better than those covering everything — but there was no way to measure this effect precisely. Only the development of technology and leaked Google API documentation pointed to a new way of looking at website topics through data. Thanks to this, we learned that metrics such as Site Focus and Site Radius exist. Discover how they work and how they can support SEO and improve online visibility!

Topical Authority in Light of the Google Leak

In May 2024, the SEO industry hit an unprecedented turning point. The leak of over 2,500 pages of Google’s internal technical documentation (the "Google Search API Leak") effectively ended the era of speculation surrounding topical authority.
 
The revealed definitions confirmed that modern search engines no longer view a website solely as a link graph (the classic PageRank model). In today’s Information Retrieval framework, a site is analyzed as a vector in a multi-dimensional mathematical space.
 
Among the thousands of leaked attributes, Site Focus (referenced as siteFocusScore) emerged as a critical quality parameter. It is a mathematical metric that draws a hard line between expert-led services and generalist sites. The documentation also introduces Site Radius (siteRadius), which complements Site Focus by describing the degree of topical dispersion of content within a domain.
 
What does this mean in practice? Let’s dive in.
 

What is Site Focus?

The siteFocusScore parameter is a numerical value that defines a domain’s level of thematic concentration. Put simply, it’s a metric that answers one core question: Is this website a specialized expert in a single field, or just another generalist portal?
 
To understand how this mechanism works, let’s use a light analogy:
 
  • High Site Focus (The Laser Effect): Imagine a site that publishes content exclusively on one topic—for example, specialty coffee brewing. Every article is thematically interconnected. The "energy" of this site acts like a laser—narrow, but incredibly powerful and precise. For algorithms, such a site is the undisputed authority in its niche.

  • Low Site Focus (The Lightbulb Effect): On the other end of the spectrum are multi-topic portals covering everything from construction to high fashion. Their content is scattered across the entire thematic map. They function like a standard lightbulb—they illuminate a wide area, but the light is diffused and weak. Such a site has a low focus score because it lacks a clear specialization.

High Site Focus vs Low Site Focus

Comment

Mateusz Godzic

Matuesz Godzic, Head of Growth at WhitePress®

Today, SEO is becoming an engineering of precision, and the rise of AI is only accelerating that pace. There’s no longer room for guesswork or basing strategies on hollow metrics. You need to know exactly why you’re choosing a specific portal for publication. The key is crafting content that builds authority—not just in Google, but across all channels that draw knowledge from our work. The era of manipulation and 'forcing' traffic through unrelated keywords is slowly fading. This revolution won't happen overnight, but its progress is steady and inevitable.

How is the Site Focus score calculated?

Algorithms don't read text the way humans do; they convert it into numbers. To replicate this process precisely, advanced data engineering is required. One of the ways of presenting the mechanism for calculating thematic consistency it to break it down into four key stages:
 
  • Content Extraction: The process begins by crawling the sitemap and extracting key textual data from every subpage. The goal is to isolate the "semantic DNA" of each articl
  • Vectorization (Embedding): Next, word-based representations are converted into mathematical representations called vectors, which are then embedded in a multi-dimensional space. In this environment, "meaning" equals "location"—texts with similar themes land close to one another.
  • Calculating the Centroid (The Heart of the Site): This is the most critical step. An average vector, known as the centroid, is calculated for all the vectors (pages) on a given domain. The centroid is the site’s mathematical "center of gravity." It defines the portal’s identity—the point around which all content orbits.
  • Distance Measurement: Finally, the system measures how closely individual pages sit to this centroid. The more densely the vectors are clustered around the center, the higher the Site Focus score.
With this approach, we’re no longer guessing a website’s topic — we can actually calculate it, seeing whether a portal stays on course (a dense cluster of points) or drifts in random directions. It’s worth noting that with each new calculation and new data, both Site Focus and Site Radius can change.
 
How to calculate Site Focus?

Why raw numbers aren't enough

If we relied solely on raw mathematical calculations, the result wouldn't mean much to the average user. This is because modern language models are prone to a phenomenon called anisotropy.
 
Essentially, text vectors tend to cluster in a narrow, restricted area of the vector space—often called "The Cone Effect". Because of this, even thematically different articles can show high baseline similarity simply because they share the same language and grammatical structure.
 
If you calculate Site Focus using unprocessed data in this context, you might get an abstract value like 0.064. On its own, that number is meaningless. Without a point of reference, it’s impossible to tell whether it indicates a high authority or thematic chaos.

The Solution: Calibration

To turn these numbers into actionable business insights, the results must undergo calibration (tuning). This involves establishing a reference scale by benchmarking broad, multi-topic portals against hyper-specialized niche sites.
 
By doing so, raw mathematics is translated into clear, intuitive categories. This allows users to easily distinguish between a "catch-all" portal and a strictly focused, thematic authority.

What is Site Radius?

While Site Focus describes the overall health of a website (checking for total consistency), Site Radius allows us to evaluate each article individually. It is a distance metric that calculates how far a specific subpage has "drifted" from the site’s core topic.
 
To visualize this, data analysts often turn to an astronomical analogy:
  • The Sun (Centroid): The primary subject of the website (e.g., "Automotive").
  • The Planets (Subpages): Individual articles.
  • The Orbit (Radius): The distance of a planet from the Sun.
How to interpret Radius?

  • Low Site Radius (A Tight Orbit): An article closely aligned with the core topic (e.g., a piece about tires on an automotive portal) stays close to “the Sun.” This signals that the content is relevant and fits the site’s expert profile.

  • High Site Radius (The Comet): If that same portal publishes an article completely unrelated to cars (e.g., a cooking recipe), it will end up in a very distant orbit. Its vector sits far away from the centroid.
A high Site Radius often serves as a red flag. It can indicate an attempt to manipulate rankings, a "dilution" of the site's authority, or the absence of a cohesive content strategy.
 
Low Site Radius vs High Site Radius

How to use these metrics in practice?

While Site Focus and Radius are not standalone ranking factors, they allow you to approach SEO and content marketing with a much higher degree of structure. Decisions shift away from "gut feeling" and toward analysis rooted in hard data.
 
It is important to note that these are not metrics you can pull directly from Google Search Console or standard SEO tools. They are the product of vector analysis and require processing massive datasets through embedding models. As a result, you’ll typically access them through specialized platforms—and they will soon be available directly within the WhitePress® platform!

Precision in choosing publication placements

Traditional methods of selecting a publication site—for a guest post, for example—often rely on broad categories and lack the insights provided by Site Focus and Radius. Are you looking for portals to acquire links or brand mentions to improve your visibility in AI and Google? With these metrics at your disposal, you can take your efforts to the next level. It allows you to precisely identify websites that have a high concentration of content on your specific topic.
 
What’s more, these systems can find the right place for a publication even on generalist portals by identifying content clusters that are semantically related to your article. This means that despite a lower overall Site Focus for the domain, you can still accurately choose the best spot to place a link or brand mention. It is a major step toward high-quality, precision-targeted link building.

Comment

Katarina Dahlin

Katarina Dahlin, Senior Growth Hacker & SEO Expert at WhitePress®

A few years ago, I could rank a single site for multiple unrelated topics without much difficulty. Today, this no longer works, whereas the topically focused sites are outranking broader ones, even when the broader sites have more content. The way the algorithm ranks sites has noticeably changed, making content pruning and a more critical approach to content creation essential. The same principle applies to link building. Choosing topically relevant publishers has become critical for link building success.

Topical Hygiene and Content Pruning

For website owners, these metrics are extremely valuable and become a powerful diagnostic tool. They allow you to precisely identify subpages that stray too far from the core topic. This makes it easier to find articles that weaken a domain’s authority — for example, outdated content that no longer fits the site’s current profile.

Often, removing content (so-called content pruning) can increase a domain’s authority more effectively than publishing new articles. In some cases, simply updating the text, merging it with other content, or placing it in a stronger thematic context is enough.

Automatic Categorization

The most significant innovation here is the move away from "self-declaration." Until now, a portal’s category depended entirely on how the publisher described it. Thanks to semantic embeddings, the content vectors themselves now define the category. The system automatically assigns a portal to the correct "semantic bucket" based on what it actually publishes, rather than what it claims to be in the footer.

Comment

Itamar Blauer

Itamar Blauer, Head of Marketing & Growth at WhitePress® (UK)

Site Focus and Site Radius provide a clearer picture of a website’s relevance based on mathematical calculations that are contextual to a site’s actual content. It allows marketers to quickly see whether a site is deeply specialised, broadly themed, or scattered across topics, and how closely it matches the subjects they want to be associated with.

Mathematics: The New Currency of SEO

The Google API documentation leak was a watershed moment, confirming that Topical Authority is a hard, calculable variable. It serves as a clear signal that SEO is increasingly becoming a field of data science rather than subjective interpretation.
 
Metrics like Site Focus and Site Radius allow us to navigate this landscape with mathematical precision. Instead of relying on intuition, the industry is gaining access to hard numbers, enabling brands to build their visibility strategically and in perfect alignment with the logic of modern search engines.
Author: Mateusz Godzic

Head of Growth, WhitePress®

With 20 years of experience in the internet industry, he is an expert in website creation, image building, and business processes. A fan of optimisation and automation. He is currently the Head of Growth at WhitePress®. In his personal life, he is a fan of double espresso, electronic music, and photography.
Author: Małgorzata Poręba

Content Creator

www.whitepress.com

She has been involved in the SEO industry for nearly 3 years. Previously, she worked at an agency as an SEO specialist, and she is currently responsible for content at WhitePress®. By passion, she is a writer with a degree in creative writing, who in her free time creates artistic texts (she runs the blog pisarzowiczka.pl) and, when time allows, enjoys drawing.
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