Visibility index: what it measures and what it stopped showing in 2025

What the visibility index is

The visibility index is a metric for how visible a domain is in Google's search results. Sistrix has tracked it since 25 February 2008, measuring thirteen countries daily and the rest weekly.

The number answers one question. How many people could theoretically see this domain on Google? It explicitly does not answer how many actually arrive. More on that below, because that is exactly where the problem sits in 2026.

How it is calculated

The calculation runs in three steps, and Sistrix documents them openly.

• Collection. Search results are pulled for around one million queries per country, up to a hundred positions each. That yields roughly 100 million data points. The keyword set is meant to reflect a cross-section of national search volume and gets refreshed regularly. (Source: Sistrix, 2026)
• Weighting. Each ranking is weighted by two things, the keyword's search volume and the expected click probability at the measured position. A first place on a heavily searched term counts for a lot, a ninetieth place on a rare one for almost nothing.
• Aggregation. All weighted rankings for a domain are added up. The sum is the index value.

Ads and special result formats do not count. The index knows organic results only.

What the number says and what it does not

This is where most of the misreadings happen. Four properties are worth knowing.

It is a zero-sum game

A fixed pool of 100,000 visibility points is distributed across every ranking domain in a country, and the pool is the same size in every country. (Source: Sistrix, 2026)

One consequence surprises many people. Your domain can lose points even though none of your rankings changed. It is enough for other domains to improve. A falling index is therefore no proof that you did something wrong.

It is not a traffic index

Sistrix says so plainly. The visibility index is not designed as a traffic index; it measures SEO performance rather than visitor numbers. In most cases the two move together, but they do not have to.

Part of the reason sits in the construction. Sistrix works with an annual average of search volume that stays constant across all months, so that ranking changes show up in isolation. That makes the index blind to seasonality. On a seasonal topic it can climb while visitors stay away, and the reverse.

Absolute values say little on their own

Sistrix deliberately names no target values and recommends comparing against your own competitors instead. In its own words, a zero before the decimal point does not mean a website is unsuccessful.

The reason lies in the keyword set. It reflects the average of an entire country, so a broad department store inevitably scores higher than a specialist with ten products. Comparing across such boundaries misleads. Across countries the value is comparable, an index of 10 in Germany equals an index of 10 in the United States.

It measures visibility, not quality

The index says nothing about the strength of your link profile. Separate metrics exist for that, such as Trust Flow. The two get confused regularly but measure different things, one presence in the search result, the other the trustworthiness of the referring domains.

Where to look it up

The visibility index in the narrow sense exists only at Sistrix; the term is their metric. Other providers have their own measures serving a similar purpose but calculating differently. For an overview of the tools and what they are good for, see our roundup of link building tools.

One thing matters when looking it up. A single value without comparison is worth little. Always pull two to five direct competitors alongside it and read the trend rather than the daily figure.

The alternatives compared

Search Console is the only source with real data. It carries one catch that became important in 2026. Google counts an appearance in an AI Overview as a single position, and every link inside it receives that same position. Your average position can improve while the clicks disappear.

What the index no longer shows in AI search

This is the part that puts the metric in question in 2026. Two statements from the same provider sit side by side.

Sistrix wrote in May 2025 that AI Overviews do not displace organic results and are therefore not counted in the visibility index. That statement still stands unchallenged in the documentation, and the underlying calculation has not changed since 2008. (Source: Sistrix, 2025)

In February 2026 Sistrix published an analysis of more than 100 million keywords in the German index. The findings:

• The click rate on position 1 falls from 27 to 11 percent when an AI Overview appears. (Source: Sistrix, 2026)
• Across all keywords that costs Germany around 265 million organic clicks per month, an average of minus 6.6 percent. (Source: Sistrix, 2026)
• The spread is enormous. Some portals lose around one percent, health sites up to more than 30 percent. (Source: Sistrix, 2026)

Put together, the two statements describe the gap. The position stays the same, the search volume stays the same, so the index value stays the same. The click, however, is gone. The very quantity the index models through its click weighting has changed without the index changing.

How solid is the evidence?

For a long time only correlations existed, and those carry a known weakness. Queries showing an AI Overview skew informational, and informational queries always produced fewer clicks. Semrush pointed exactly at that and found in its own analysis a slight decline in the zero-click rate, from 33.75 to 31.53 percent. (Source: Semrush, 2025)

Since June 2026 there is a clean answer. A randomised field experiment with 1,065 participants, in which AI Overviews were stripped out live via a browser extension, finds organic clicks dropping by 39.8 percent, from 0.62 to 0.37 clicks per search. The study is preregistered and not yet peer reviewed. (Source: Agarwal and Sen, 2026)

Two side findings are telling. Clicks on ads stayed unchanged, so the shift hits organic results alone. And Google's argument that AI answers deliver better clicks in return did not hold up. Time on page, bounce rate and return rate showed no difference.

Ahrefs measures a 58 percent drop in click rate at unchanged position, across 300,000 keywords using Search Console data. The same provider had measured 34.5 percent in 2025 and revised the figure upward itself. (Source: Ahrefs, 2026)

None of this is an obituary for the metric. For competitive comparison it still works, because every domain in a market is affected alike. As an answer to whether visitors arrive, it has weakened. And it says nothing about whether your brand appears in AI answers at all. What counts there is covered in our piece on visibility in AI systems.

How to measure visibility today

One consequence follows from all this. A single number no longer suffices, it takes two side by side.

The first is classic visibility in the search result, where the visibility index remains the established yardstick for comparison. The second is visibility in AI answers, meaning whether your brand gets named when someone asks a language model about your topic.

MentionIQ covers both. It analyses your website and your competitors, shows your backlink gaps and your visibility gaps against the competition, both in classic SEO visibility and in visibility inside large language models and AI search. On that basis it recommends suitable placements. How to track the development continuously is shown by our monitoring.

How to read the number from now on

Three things. The visibility index remains the best available yardstick for comparing yourself with competitors. It is not a traffic measure and was never meant as one, which matters more in AI search than it used to. And it does not answer whether your brand appears in AI answers.