Share of Voice

Share of voice: your portion of the ad real estate for a given search term, relative to every advertiser competing on it.

You measure how often your ad occupies a placement, often top of search, as a percentage of the total impressions or slots available for that keyword over a period. It tells you how much of the visible shelf for a term you are holding, which pure spend and ACoS numbers do not show.

Your ad holds the top-of-search slot for a keyword 30 percent of the times it is searched. Your share of voice for that placement is 30 percent.

Share of voice is not sales. You can buy more impressions and raise it without lifting conversion at all, and definitions differ by tool, some counting impression share, others counting placement share. In 2025 Amazon added a Sponsored Brands option to reserve share of voice directly, which changes how the top slots get allocated.

Owning the shelf is a means, not the result. Track it, but pay yourself in conversions.