Reference library · Media planning
Share of Voice (SOV)
Share of Voice (SOV) is a brand's advertising spend or weight as a percentage of total category advertising spend or weight, in a given medium, market and period. It quantifies competitive visibility, not effectiveness, and is calculated separately per medium because TV GRPs, digital impressions and spend cannot be summed across channels. Planners use it to benchmark investment against named competitors and to size the budget needed to defend or grow market share.
Formula
Worked example
Czech yogurt category, TV, Q2: Brand A (client) spends €1.1m, Brand B €1.5m, Brand C €0.9m, Brand D €0.7m, all others €0.8m, for a category total of €5.0m. Brand A's SOV = 1.1m / 5.0m x 100 = 22%. Brand A's share of market (sales value) that quarter is 18%, so its excess share of voice (ESOV) is +4 points, a level consistent with holding or slowly growing share rather than defending a decline.
How it is used
SOV is tracked per medium against a defined competitive set, then read next to share of market (SOM) as excess share of voice (ESOV = SOV - SOM): sustained ESOV above zero over a year or more, not one flight, is what correlates with share growth. Planners use it to size annual budgets, flag when a competitor's launch is overwhelming the category, and support weight requests in budget negotiations. The recurring error is building one brand's SOV from list-rate GRPs and a competitor's from net spend, or blending TV and digital into a single percentage, which distorts the comparison because unit costs and reach differ by medium.
The common mistake
Calculate SOV from net (actual) spend or comparable weight units within a single medium, not from list-rate spend or a cross-media blend, or the result misstates who is really outspending whom.