SEO Visibility Index: What It Measures and What It Misses

Blog · SEO visibility index

An SEO visibility index is a single score that summarises how present a domain is in Google's organic results. The best documented version comes from Sistrix, which introduced it in 2008: the tool records the organic results for about one million search terms, weights every ranking by search volume and by how likely a click is at that position, and adds everything up. Other tools such as Semrush use the word visibility for related scores that work differently. You can check the index for any domain, including your competitors. What it does not tell you is how many visitors you get, and it says nothing about whether ChatGPT or Google's AI Overviews mention your business.

In brief

A visibility index adds up weighted rankings across a fixed or self-chosen set of keywords, so it reflects how often and how high a domain appears, not how many people click.
Sistrix uses a fixed set of about one million keywords per country; Semrush calculates visibility from the keywords you track in your own project, so the two scores cannot be compared.
Seasonality is averaged out, local results are not covered, and niche topics are often thinly represented in the keyword set.
According to Sistrix, AI Overviews are not counted in its Visibility Index, and ChatGPT answers sit outside Google entirely. They need a separate measurement.

Published 9 Oct 2026Nikolai Schöbel and Jeremias Burger8 min read

Nikolai Schöbel and Jeremias Burger

Co-founders of Scalableloops GmbH. Nikolai Schöbel leads online marketing and AI strategy, Jeremias Burger the AI architecture. Both build AI systems and train teams on them in their own agency work.

On this page

What an SEO visibility index tells you about your search presence
How the Sistrix Visibility Index is calculated, so you can read it correctly
How to check your visibility index quickly
Sistrix, Semrush and other visibility scores: why you should not mix them
What a visibility index does not show, and how to avoid wrong conclusions
Why your visibility index leaves out AI search visibility
Complement your visibility index to see the full picture
Frequently asked questions
How to use a visibility index for real decisions
Where the information on this page comes from

Basics

What an SEO visibility index tells you about your search presence

An SEO visibility index tells you how strongly your domain shows up in Google's organic results, condensed into one score you can follow over months and years. Some write-ups describe search visibility as the share of clicks a site earns from its rankings: if you rank third for a keyword and that position typically gets a certain share of clicks, that share is your visibility for the keyword. A visibility index does the same across thousands or millions of keywords at once.

Because the score is built from what Google shows publicly, you can look it up for any domain, your competitors included. That is the real strength of the metric. Your analytics only ever show your own site, while a visibility index lets you put your trend line next to theirs.

Keep one distinction in mind from the start. Sistrix says plainly that its Visibility Index is not a traffic index: it measures SEO success, not visitors. In most cases the two move together, but they do not have to, and most misreadings of the score begin with forgetting this.

Calculation

How the Sistrix Visibility Index is calculated, so you can read it correctly

The Sistrix Visibility Index calculation is openly documented and runs in three steps. First, Sistrix collects the Google results for about one million keywords per country, usually the top 100 organic results for each, which gives roughly 100 million data points. The keywords are chosen to form a representative cross-section of search volume in that country, and part of the set is replaced regularly to follow changes in demand.

Next, every ranking is weighted by the keyword's search volume and by the expected click probability at that position. Position eight on a heavily searched term can therefore be worth more than position one on a term almost nobody types. Search intent plays a part too, since people looking for a specific website tend to click only the first result, while people researching a topic scroll further. Finally, all weighted values for a domain are added up.

Two consequences are easy to miss. Sistrix distributes a fixed pool of 100,000 visibility points across all ranking domains, so your score can fall without you losing a single ranking, simply because others gained. And because every country gets the same pool, Sistrix states that a score of 10 in Germany means the same visibility as a score of 10 in the US, even though the traffic behind it differs with market size.

Step	What happens	What it means for you
Collect	Organic Google results for about one million keywords, usually the top 100 each	Only keywords in that set count, which may not include your most important ones
Weight	Search volume and click probability of the position, adjusted for intent	A few strong rankings can move the score more than many weak ones
Add up	Sum of all weighted rankings of a domain	A drop can come from competitors gaining, not from you losing

Checking

How to check your visibility index quickly

To check your visibility index, Sistrix offers a free lookup page where you enter a domain and see the current score with its history, without creating an account. For actual analysis you need the full tool, because only there can you see which keywords carry the score, how directories and single URLs perform and where competitors gained ground.

Never look at your own number in isolation. A value like 0.4 says little on its own; it starts to mean something next to two or three direct competitors and as a trend over several months. Sistrix updates the index daily for the larger markets, including the US, UK and Germany, with separate values for mobile and desktop.

If the keywords that matter most to your business do not appear among those that carry your score, build an index from your own keywords instead. Sistrix projects can be set down to city level, and Semrush calculates its visibility score in Position Tracking from the keywords you choose yourself.

Comparison

Sistrix, Semrush and other visibility scores: why you should not mix them

Semrush visibility, the Sistrix Visibility Index and similar scores share a name but not a formula. Sistrix works from a fixed, market-wide keyword set. Xovi's OVI uses a fixed set of 500,000 keywords and the top 50 results, collected weekly. Semrush, by contrast, bases its visibility on the keywords in your own project, so two accounts with different keyword lists will report different visibility for the same domain.

The practical rule follows from that: pick one tool per question and compare domains only within it. A Sistrix score of 3 and a Semrush visibility of 30 percent cannot be converted into each other, and switching sources between reports creates differences that come purely from the method.

Score	Keyword set	Results counted	Typical use
Sistrix Visibility Index	Fixed, about one million per country	Usually the top 100 organic	Market-wide comparison, history back to 2008 in Germany
Xovi OVI	Fixed, 500,000 per search engine	Top 50, weekly	Market-wide comparison with a smaller set
Semrush visibility	Your own tracked keywords	Depends on the project	Progress on your target keywords

Limits

What a visibility index does not show, and how to avoid wrong conclusions

A visibility index does not show visitors, and seasonality is part of the reason. Sistrix uses an annual average of search volume so that ranking changes stand out cleanly, which means seasonal peaks disappear from the score. A garden centre can get far more visits in spring while its index stays flat.

The index is also calculated for a whole country. Local results, which Google shows differently depending on where someone searches (a search for a hotel in Boston returns different results than the same search in Denver), are not reflected. For a business that mainly wants to be found in its region, the general index says little about how well that is working.

Niche topics are often thinly covered, too. If you sell specialist parts to a small industry, your key terms may not be in the keyword set at all, and a low score then only means the measurement does not capture your market. And the index says nothing about whether a visit turns into an enquiry (for that you need your own analytics).

AI search

Why your visibility index leaves out AI search visibility

Your visibility index counts organic Google results only; according to Sistrix, ads and other elements of the results page are not included. For AI Overviews, Sistrix stated in May 2025 that they do not displace organic results and are therefore not counted in the Visibility Index. Whether your page is cited as a source in an AI Overview is simply not part of the score.

That matters because AI Overviews change click behaviour. A Sistrix analysis of the German market published in February 2026 found AI Overviews on about a fifth of keywords, and the click-through rate of the first organic result dropping from 27 to 11 percent when one appears, roughly 265 million fewer organic clicks a month in Germany. Your ranking stays the same, your index stays the same, and fewer people reach your site.

Answers from ChatGPT, Perplexity or Gemini sit outside Google's results altogether and cannot appear in the index. Even Sistrix and Semrush treat this as a separate question: both track mentions in AI answers in dedicated products. For how these Google features work, see our posts on Google AI Overviews and Google AI Mode.

11 %

click-through rate of the first organic result when an AI Overview appears, down from 27 percent without one.

Sistrix, analysis of the German market, February 2026

Next step

Complement your visibility index to see the full picture

Complement your visibility index with two more views. Google Search Console shows real clicks and impressions for your own site, and Google says appearances in AI Overviews and AI Mode are included in your overall search traffic there, in the Performance report under the Web search type. It shows no competitors, though, and its numbers move with demand, which is why Sistrix describes the two tools as answering different questions.

The third view is whether AI systems name your company when someone asks about what you offer. That can only be measured by asking real questions and analysing the answers, and we describe how we approach it in how to measure AI visibility. If you would rather not build this analysis yourself, our GEO agency team runs it and gives you the current status alongside your competitors.

01
Visibility index
How present am I on Google compared with others?
Market-wide competitor comparison and trend, without visitors, location or season.
02
Google Search Console
How many people see and click my site?
Real clicks and impressions for your own site, AI Overviews included, no competitors.
03
AI visibility analysis
Do ChatGPT and others mention my company?
Mentions and sources in AI answers, measured with real questions across several systems.

Frequently asked questions

What is an SEO visibility index?

A score that summarises how present a domain is in Google's organic results. The best known version, the Sistrix Visibility Index, adds up weighted rankings for about one million keywords per country.

How can I check my visibility index for free?

Sistrix has a free lookup page that shows the current score and history for a domain without an account. For keyword-level detail and competitor analysis you need the full tool.

What is a good SEO visibility score?

There is no fixed target. A score only becomes meaningful next to your direct competitors and as a trend over several months.

Why did my visibility drop when my rankings stayed the same?

Because Sistrix distributes a fixed pool of visibility points across all domains. If others gain, your share can shrink without you losing a single position.

Is search visibility the same as traffic?

No. A visibility index measures presence in the results, averages out seasonality and ignores local results. Visits show up in Search Console and in your analytics.

Are AI Overviews included in the visibility index?

According to Sistrix they are not, as of May 2025, because they do not displace organic results. ChatGPT answers are outside Google anyway and need their own measurement.

What now

How to use a visibility index for real decisions

01
Check the score
Look up your domain and two or three direct competitors, and review the trend over at least a year.
02
Explain the swings
When the score jumps, check which keywords are behind it and whether a Google update, a relaunch or a competitor caused it.
03
Compare with real data
Hold the trend against clicks and impressions from Search Console so you keep visibility and actual visits apart.
04
Measure AI answers separately
Ask the main AI systems about your service regularly and record whether and how your company is mentioned.

A visibility index is still a good ruler for comparing yourself on Google. Where your customers get their answers today, it only measures part of the way.