The Visibility Index is a single number that estimates how prominently a website appears in Google's organic search results. It exists because rankings on their own are hard to read: a site may rank for hundreds of thousands of queries, at different positions, for terms of very different popularity. The index compresses all of that into one figure that can be charted daily and compared across competitors. The best-known version, and the one the term usually refers to, belongs to SISTRIX, a search analytics company in Bonn, Germany, which describes itself as the inventor of the metric. Several rival vendors publish scores with similar names and different arithmetic.

The figure is not a traffic count. SISTRIX itself says the index "is not a traffic index" and measures SEO success rather than visitors. It models potential exposure from a fixed keyword sample, not from any site's analytics.

How the index is calculated

SISTRIX publishes the outline of its method, though not the exact weights. The calculation runs in three stages.

Collection. For each country, SISTRIX maintains a keyword set of one million terms, chosen to form what the company calls a "representative cross-section of the search volume." A portion of the set is swapped out regularly as demand shifts. For each keyword, the crawler records the organic Google results, usually the top 100. That yields 100 million data points per country.

Weighting. Each data point is weighted by two values: the keyword's search volume and the expected click-through rate (CTR) for that organic position. A ranking in position 8 for a high-volume query such as "nintendo switch" therefore scores more than position 1 for a long-tail query like "nintendo switch memory card recommendation," according to SISTRIX's own example. The company also adjusts for intent. Navigational searches, where the user wants a specific website, tend to concentrate clicks on the first result, while informational searches spread clicks further down the page.

Summation. The weighted values for every ranking a domain holds are added together. SISTRIX distributes 100,000 visibility points across all rankings found in a country, so the scores of all domains in a market share a fixed pool. Every domain ranking for at least one keyword receives a value, and partial values exist for subdomains, directories and URLs.

Because the pool is fixed, one site's gain is another's loss. When a Google feature pushes an organic result down, SISTRIX assigns the displaced points to an internal virtual domain. And because each country gets the same pool, a score of 10 in Germany represents the same share of visibility as 10 in the US, though not the same number of visitors.

Search volume is an annual average, so seasonality is smoothed out by design.

A worked illustration

Consider a hypothetical domain ranking third for a heavy-volume keyword, first for a mid-volume term and fifteenth for a rare one. The position-15 ranking contributes almost nothing, since expected CTR on page two is close to zero, and the position-3 ranking may outweigh the position-1 ranking. If the domain slips from 3 to 6 on the busy query, its score can fall sharply while its average position barely moves. That sensitivity to where volume sits is the point of the metric.

Scale and typical values

There is no fixed range. In the UK, after Google's December 2025 core update, the Guardian stood at 228.9, the Telegraph at 43.9 and BBC News at 34, based on SISTRIX data analysed by Press Gazette and reported in PPC Land's coverage of British publisher losses. In Germany, Amazon lost 607 points in the first half of 2026, a 20% fall that let YouTube take second place in the SISTRIX Top 100 Domains ranking. Taken together with the 100,000-point pool, that implies Amazon held roughly 3% of all measured German organic visibility before the drop; that share is an inference from the published figures, not a number SISTRIX states.

Devices, countries and update frequency

The index began as a desktop measure. SISTRIX added a smartphone index on March 17, 2015, and countries added from 2018 are measured on mobile only. On September 22, 2025, SISTRIX stopped systematic desktop SERP updates and eliminated the desktop index altogether, according to PPC Land's report on the num=100 fallout. Some of SISTRIX's own documentation still describes desktop data, so its pages lag the product on this point.

The company's coverage figures also disagree. Its calculation page lists 52 countries, each measured in one language; its overview and strengths pages say 40. The calculation page says 13 original markets, including Germany, the UK and the US, receive daily updates while 39 later additions are updated weekly, but the strengths page describes daily data without that qualification. Daily figures are kept for 90 days, with Monday's value archived permanently.

Origin and evolution

The index began as a side project. In 2007, SISTRIX founder Johannes Beus set up automated monitoring of the top 100 Google results for 1,000 keywords, a free prototype called IndexWatch. Data collection for the index proper started on February 25, 2008, in Germany, where it is known as the Sichtbarkeitsindex. Beus then widened the keyword set and introduced per-keyword weighting.

Expansion followed: Spain, France, Italy and Great Britain on September 13, 2010; Austria and Switzerland in 2011; Poland, Brazil, Sweden, Turkey and the Netherlands in 2015. SISTRIX says the basic formula has not changed since 2008, which makes the history "fully comparable" across nearly two decades.

The metric gained international prominence in February 2011, when Danny Sullivan of Search Engine Land used SISTRIX data to list the losers of Google's Panda update. Wisegeek.com fell 77%, Suite101 94% and EzineArticles 90%, according to that analysis. Winners-and-losers tables built on visibility scores have since become the standard way the industry narrates algorithm updates.

The hardest operational test came in September 2025, when Google stopped supporting the num=100 URL parameter, which had let crawlers retrieve 100 results in one request. SISTRIX briefly recorded only the top 10, then rebuilt its crawling so that index keywords still capture 100 positions, restoring daily data for 12 countries by September 19.

Why it matters for marketers

The index is a shared reference. Agencies benchmark clients against competitors whose analytics they cannot see, and publishers, investors and journalists use it to judge core updates. When Google's March 2026 core update wrapped, the New York Times and the Guardian were identified as leading gainers on the basis of SISTRIX visibility charts. During the May 2026 core update, SISTRIX tracked 8,887 domains and counted 5,039 winners against 3,845 losers at the halfway point.

Limitations and criticisms

The most common objection is that visibility is not traffic. SISTRIX concedes that traffic analysis can be "much more precise," while maintaining that visits correlate "strongly" with the index "in most cases."

The gap has widened as Google's results page fills with non-organic elements. The index excludes paid ads, Top Stories, Google Discover and AI Overviews, as PPC Land's coverage of the December 2025 update noted. For news publishers, much of whose traffic arrives through Top Stories and Discover, the score can move in a different direction from actual visits. AI Overviews pose a sharper problem. SISTRIX's own analysis found that position one's CTR drops from 27% to 11% when an AI Overview appears, yet a site holding the top organic position is credited with the same position whether or not an AI summary sits above it. The documentation reviewed for this article does not say whether the CTR curve is adjusted for AI Overviews.

Coverage is a second weakness. SISTRIX notes that low-volume topics may be "too low to be sufficiently represented" and recommends custom project indices. Trending terms are excluded, local variation is ignored at country level, and only Google is measured by default.

A third issue is opacity. The CTR values are not published, so independent replication is impossible, and scores from different vendors cannot be compared.

Visibility Index versus similar terms

  • SEO Visibility (Searchmetrics). Searchmetrics, an SEO software company acquired by Conductor in February 2023, built a rival index combining search volume, position and CTR modelling, recalculated weekly, with paid, mobile and local variants. It is a different formula on a different keyword set, and its values are not interchangeable with SISTRIX scores.
  • Visibility in Semrush Position Tracking. This is a percentage from 0% to 100% calculated on a user's own target keywords, where 100% means ranking first for all of them. It measures a chosen list, not a market. Semrush, owned by Adobe since April 2026, also publishes an "AI Visibility Index," a report on brand mentions in AI answers unrelated to organic rankings; that sense is covered in Explaining AI visibility.
  • Amazon Visibility Index. SISTRIX applies the same logic to Amazon product search across five European marketplaces, distributing one million points across products.
  • Viewability. An ad-measurement term for whether a served impression had the chance to be seen on screen. It is unrelated to search rankings; see Explaining viewability.

Recent developments

The index is being repackaged for an AI-driven workflow. In May 2026, SISTRIX opened its MCP server to all customers, switching authentication to OAuth so that any account, including the entry-level Start plan, can query Visibility Index data from assistants such as Claude or ChatGPT without an API key. Its February 2026 review, marking the index's 18th anniversary, said measurement now extends to Amazon and to presence in AI systems.

The index still sets the terms of update coverage. Aleyda Solis used SISTRIX data to show the March 2026 core update hit aggregators harder than December's. As of October 2026, the open question is whether a metric designed around ten blue links can still represent a results page where much of the attention goes elsewhere.

Timeline

  • 2007: Johannes Beus begins automated monitoring of the top 100 Google results for 1,000 keywords, a prototype called IndexWatch.
  • February 25, 2008: Data collection for the SISTRIX Visibility Index begins in Germany.
  • September 13, 2010: Index expands to Spain, France, Italy and Great Britain.
  • February 26, 2011: Search Engine Land publishes Panda update losers using SISTRIX visibility data.
  • 2011: Austria and Switzerland added.
  • March 17, 2015: SISTRIX launches the Smartphone Visibility Index.
  • 2015: Poland, Brazil, Sweden, Turkey and the Netherlands added.
  • September 7, 2016: Daily visibility data introduced for Germany.
  • 2018: New countries added on a mobile-only basis.
  • February 7, 2023: Conductor announces its acquisition of Searchmetrics, owner of the rival SEO Visibility metric.
  • September 14, 2025: Google stops supporting the num=100 parameter.
  • September 17-19, 2025: SISTRIX restores daily visibility data across 12 countries.
  • September 22, 2025: SISTRIX eliminates the desktop Visibility Index.
  • February 2026: The index marks its 18th anniversary.
  • April 28, 2026: Adobe completes its acquisition of Semrush.
  • May 2026: SISTRIX opens its MCP server, including Visibility Index queries, to all subscription tiers.
  • June 30, 2026: SISTRIX Top 100 Domains report shows Amazon down 607 points in Germany.

Summary

  • Who: SISTRIX, the Bonn company founded by Johannes Beus, created and operates the dominant Visibility Index. SEO agencies, in-house teams, publishers and journalists use it; Searchmetrics (Conductor) and Semrush publish rival scores.
  • What: A score that sums a domain's Google organic rankings across a one-million-keyword sample per country, each weighted by search volume and expected click-through rate, from a fixed pool of 100,000 points.
  • When: Data collection began on February 25, 2008, in Germany. A smartphone index followed in 2015, daily updates in 2016, and the desktop index was retired in September 2025.
  • Where: Google's organic results in 40 to 52 countries, depending on which SISTRIX page is cited, with a separate index for five European Amazon marketplaces.
  • Why: It turns hundreds of thousands of rankings into one comparable number, enabling competitor benchmarking and update analysis without access to anyone's analytics, at the cost of ignoring AI Overviews, ads, Discover and actual traffic.