Share of voice(SoV)

Long definition

Share of voice borrows from advertising — where it meant your spend or impression share within a category — and applies the concept to organic SERPs. The intuition: across a fixed list of keywords your category cares about, what fraction of the visible SERP estate belongs to you versus each competitor?

Two layers determine the number:

Layer 1: the keyword universe. A keyword set of 50 head terms gives a different SoV than a keyword set of 5,000 head + long-tail. The universe should match the strategic question. Tracking SoV against "the queries our buyers run" is useful; tracking SoV against "every keyword in our category" is noisy and dominated by long-tail variations no one targets.

Layer 2: the weighting formula. Common variants:

• Volume × position-CTR. Position 1 on a 10,000-volume keyword contributes more than position 1 on a 100-volume keyword. The most common formulation. Position-CTR curves are tool-specific estimates.
• Visibility points. Position-only weighting, ignoring search volume. Useful when comparing competitors with similar query distributions.
• Estimated traffic share. Volume × CTR estimates summed across the keyword set. Closer to a business metric, sensitive to CTR-curve assumptions.

Each major SEO tool publishes its own SoV variant: Ahrefs Share of Voice, Semrush Visibility, Sistrix Visibility Index, Moz Share of Voice. The numbers will not match across tools because the keyword universes and formulas differ. Pick one tool and one fixed keyword set, then track delta over time. Comparing absolute SoV between tools is meaningless.

For SEO programs, SoV is most useful for two questions: are we gaining or losing ground vs the named competitor set, and which competitors are taking our share. The second question requires segmenting SoV by topic cluster — a competitor gaining 5% sitewide may be gaining 30% in your most strategic cluster while losing share elsewhere.

Common misconceptions

• "SoV across two tools should match." It will not. Ahrefs, Semrush, and Sistrix use different keyword databases, different position-CTR curves, and different aggregation rules. Pick one and treat its number as a relative index, not an absolute truth.
• "Higher SoV means higher revenue." Only when the keyword universe overlaps your conversion-bearing queries. SoV in a head-keyword set you don't sell against is informational at best, vanity at worst.
• "SoV is the same as organic visibility." Organic visibility is usually a sitewide composite metric (your ranking footprint across all keywords the tool tracks). SoV is share within a defined competitive set. Visibility can rise while SoV falls if a competitor rose faster.
• "You can compare SoV month-over-month with confidence." Only if the keyword universe is locked. Many tools auto-expand the keyword set as queries trend. A SoV "drop" can reflect new keywords entering the index, not lost ground.