8.7Intermediate9 min

Share of Voice: Measuring Search Market Share

Lucas Blochberger·7 April 2026·Updated 12 June 2026

Definition

Share of Voice (SoV) in SEO measures the percentage of total organic visibility a brand captures for a defined keyword set compared to competitors. It serves as a proxy for market share in organic search.

Key Takeaways

✓Share of Voice measures the relative share of organic visibility compared to a defined competitor set, not isolated own performance.
✓The calculation follows four steps: define keyword set, weight by search volume, apply position-dependent CTR, and account for SERP features; the basic formula is own clicks divided by total clicks of the set.
✓The SISTRIX Visibility Index is an absolute value per domain (100 million daily data points), while SoV is always measured relatively as a percentage share; SoV can be derived from the index.
✓Tool-based SoV is an estimate based on modeled CTR curves and must be validated against real data from Google Search Console and GA4.
✓AI Overviews reduce the CTR of the top-ranking page by up to 58 percent and decouple ranking from clicks; traditional SoV should therefore be supplemented by an AI visibility metric (AI Answer Inclusion Rate).
✓With 81.87 percent Google market share in Austria, SoV is effectively a Google market share; in B2B niches with low search volume, a narrow, business-relevant keyword set is crucial for stable values.
✓SoV delivers the greatest value operationally: for identifying content gaps and competitive gaps, and as a medium-term trend KPI for SEO ROI.

Share of Voice provides strategic overview: How does your website compare to the competition?

Calculate SOV

Define a relevant keyword set. Measure the estimated organic CTR for each keyword based on your position. Compare with competitors. Your share of total organic visibility = SOV.

Sistrix Visibility Index

In the DACH region, the Sistrix Visibility Index is the standard SOV metric. It aggregates rankings and search volumes into a single comparable value. Historical data since 2008 enables long-term comparisons.

Share of Model: SOV for AI

Share of Model extends the SOV concept to AI search systems. It measures how frequently a brand is mentioned in AI-generated answers, compared to competitors. Tools: Profound, Ahrefs Brand Radar, Semrush AI Visibility.

Data & Statistics

Google 81,87 %, Bing 9,01 %, DuckDuckGo 2,75 % Suchmaschinen-Marktanteil in Oesterreich

StatCounter Global Stats - Search Engine Market Share Austria (2026)

SoV = geschaetzte eigene organische Klicks / gesamte Klicks des Keyword-Sets; Beispiel 6.000 von 100.000 = 6 %; Methodik aus Rankings, Suchvolumen, SERP-Features und positionsabhaengiger CTR

Semrush - How to Measure SEO Share of Voice (2025)

1.000.000 Keywords x 100 Treffer = 100 Mio. Datenpunkte, gewichtet nach Suchvolumen und Klickwahrscheinlichkeit, taeglich seit 2016 berechnet, Methodik seit 2008 unveraendert

SISTRIX - Berechnung des Sichtbarkeitsindex (2025)

Top-3-Ergebnisse erhalten 68,7 % aller Klicks

Ahrefs - 107 SEO Statistics for 2026 (2026)

Position-1-CTR sank von 28 % (2024) auf 19 % (2025), -32 %; Position 2 von 20,83 % auf 12,60 %, -39 %

GrowthSRC - Google Organic CTR Study (200K Keywords) (2025)

Bei vorhandenem AI Overview 58 % niedrigere durchschnittliche CTR der Top-Ranking-Seite (300.000 Keywords, Dez 2023 vs. Dez 2025)

Ahrefs Blog - AI Overviews Reduce Clicks (2026)

Mit KI-Zusammenfassung 8 % Klick auf klassisches Ergebnis vs. 15 % ohne; 1 % Klick auf KI-Antwort-Link (n=900 US-Erwachsene, Maerz 2025)

Pew Research Center (2025)

AI-Overview-Trigger-Rate: 6,49 % (Jan 2025), 24,61 % (Jul 2025), 15,69 % (Nov 2025), Basis 10 Mio.+ Keywords

Semrush - AI Overviews Study 2025 (2025)

60 % Zero-Click-Suchen 2025, zuvor 58 % 2024

SEO Sherpa - B2B SEO Statistics (2026)

81 % der B2B-Marketer: SEO-Leads hoeherwertig als PPC; SEO-Close-Rate 14,6 % vs. 1,7 % Outbound

SEO Sherpa - B2B SEO Statistics (2026)

8,69 Mio. Internetnutzer und 95,3 % Internetpenetration in Oesterreich (Januar 2025)

DataReportal - Digital 2025: Austria (2025)

Nur 1,74 % neuer Seiten erreichen binnen eines Jahres die Top 10; 72,9 % der Top-10-Seiten sind aelter als 3 Jahre

Ahrefs - 107 SEO Statistics for 2026 (2026)

FAQ

What is Share of Voice in SEO?

Share of Voice (SoV) measures a website's share of organic search visibility compared to its competitors for a defined keyword set. The metric is relative and expressed as a percentage. It weights rankings by search volume, position-dependent click probability, and SERP features, thus showing the relative market share of a topic in search.

How do you calculate Share of Voice?

The basic formula is: own estimated organic clicks divided by total estimated organic clicks of the keyword set, expressed as a percentage. In practice, the calculation follows four steps: define keyword set, weight each keyword by search volume, apply position-dependent CTR, and account for SERP features. Semrush gives the example of 6,000 out of 100,000 estimated clicks, which equals a SoV of 6 percent.

What is the difference between Share of Voice and the SISTRIX Visibility Index?

The SISTRIX Visibility Index is an absolute index number per domain based on approximately 100 million daily calculated data points, not a percentage share. Share of Voice, on the other hand, is always relative and sets own visibility in relation to a competitor set. A SoV can be derived from the Visibility Index by dividing one's own index value by the sum of index values of all relevant competitors.

Which tools measure Share of Voice in the DACH region?

In the DACH region, Semrush Position Tracking, Ahrefs Rank Tracker with Brand Radar, and SISTRIX dominate. Semrush and Ahrefs deliver direct SoV percentage values for a self-defined keyword and competitor set. SISTRIX provides absolute Visibility Index values from which SoV can be calculated. All three work with estimated CTR curves, which is why validation against Google Search Console and GA4 is advisable.

How do AI Overviews affect the validity of Share of Voice?

AI Overviews decouple ranking and clicks. According to Ahrefs, the average CTR of the top-ranking page is 58 percent lower when an AI Overview is present. A click-based SoV thus underestimates visibility that occurs in AI answers without generating clicks. Therefore, traditional SoV should be supplemented from 2026 onwards by an AI visibility metric such as the AI Answer Inclusion Rate, which measures how often a brand appears in AI answers.

Why is Share of Voice particularly relevant for Austrian B2B SEO?

In Austria, 81.87 percent of the search market is attributed to Google, so SoV can practically be reduced to Google. Since 81 percent of B2B marketers rate SEO leads as higher quality than PPC, and SEO leads close at 14.6 percent compared to 1.7 percent for outbound, high SoV in purchase-phase keywords means access to the highest-quality lead channel. The challenge lies in the often low search volumes in B2B niches, which require a narrow, business-relevant keyword set.

What are the most common mistakes in Share of Voice measurement?

The most common mistakes are: a skewed keyword set that overemphasizes own strengths, lack of separation between brand and non-brand keywords, ignoring device- and location-dependent SERPs, blind trust in estimated tool values without cross-checking with real data, and zero-click blindness. Since 60 percent of searches end without a click, high SoV can coincide with declining real traffic when the SERP provides the answer itself.

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