What it means
TACoS (Total Advertising Cost of Sale) compares your ad spend to your TOTAL Amazon revenue — including organic sales: TACoS = ad spend ÷ total revenue × 100. Example: €300 ad spend against €1,500 total revenue (€600 ad-attributed + €900 organic) gives a 20% TACoS. The metric is strategically valuable: a falling TACoS at stable ad spend shows your advertising is fueling organic sales. A rising TACoS at constant ACoS is a warning sign — organic sales are stagnating; check your product page, reviews, and stock availability.