What coefficient links the cost of the campaign to the revenue earned?

ACOS (Advertising Cost of Sales) is the coefficient that directly links the cost of a campaign to the revenue earned. It is calculated as (Ad Spend / Ad Revenue) 100%, providing a clear percentage of how much you spend on ads for every unit of revenue generated. A lower ACOS indicates a more efficient campaign. Clicks/sales and Sales/clicks are ratios that relate clicks to sales, but they do not directly represent the cost-to-revenue relationship in a single coefficient. Clicks/sales (or click-through rate) measures engagement, while Sales/clicks (or conversion rate) measures the effectiveness of clicks in generating sales, neither of which directly incorporates advertising cost.