How to use the share of voice calculator
Share of voice is your slice of category impressions: your brand impressions รท total category impressions ร 100. Because the denominator is the whole market, your SoV can fall even when your own impressions hold steady, simply because a rival spent more.
The metric most often confused with it is impression share. That one divides impressions you won by the impressions you were eligible to receive, so its denominator is your own opportunity. SoV measures how loud you are in the market; impression share measures how little of your own chance you wasted. They are not interchangeable.
Enter a target share and the tool works backwards to the impressions you would need, holding competitor impressions constant. Your own growth also raises the category total, so freezing the total instead would understate how much more you need.
If you are already past the target, the row switches to show the surplus rather than a shortfall. Category totals are estimates whatever the source, so the trend measured the same way over time is usually more useful than the absolute number.
Frequently asked questions
SoV divides your impressions by the whole category, while impression share divides the impressions you won by the impressions you were eligible for. One denominator is the market, the other is your own opportunity.
Keyword volume tools and industry reports, all of which are estimates. The result is only as good as the denominator you entered, so it works best for tracking a trend from one consistent source.